Milford Public Schools Curriculum Department: SCIENCE Course Name: Grade 8 Course Description Physical Science UNIT 1 - Motion LEARNING GOALS Enduring Understanding(s): Motion is relative to a reference point. Motion can be described in different ways, including its speed, velocity, and acceleration. Speed is calculated as distance divided by time and can be visually represented by motion graphs. Essential Question(s): When does motion occur? How is motion described? How is motion measured and graphed? Content: Students will know An object is said to be in motion when its position changes in relation to a point of reference. An object s motion can be described and represented graphically according to its position, direction of motion, and speed. Speed describes the change in an object s position over a period of time, and is measured in units such as meters per second or miles per hour. Velocity describes both speed and direction and can be represented on a distance vs. time graph. Steepness of the line represents the speed of the object. Horizontal line represents an object at rest. Acceleration is change in velocity over time measured in meters per second per second. Steepness of a line represents acceleration, horizontal line represents constant speed. Resultant velocity combines velocities acting on an object given the direction. The acceleration that occurs on a circular motion is known as centripetal acceleration. Motion of objects can be represented on a distance vs. time line graph, with distance traveled as the vertical ( y ) axis and time as the horizontal ( x ) axis. The steepness and slant of the motion line vary depending on the speed and direction of the moving objects. A straight horizontal line indicates an object at rest. Skills Students will be able to Identify the reference point when observing motion based upon change in distance. Differentiate between a moving reference point and a stationary reference point. Define and measure distance and time using appropriate tools and appropriate units. Utilize the metric system to make appropriate measurements and conversions (mm to cm to m to km; sec to hours to days). Identify the appropriate metric unit for a specific measurement (e.g., the distance a car travels is measured in km not cm) Describe motion of an object in terms of the amount of distance traveled in a specific amount of time. Calculate the speed of an object in meters per second. Revised 1/22/2016 Page 1 of 12
Calculate the average velocity of an object in motion. Compare and contrast speed and velocity. Identify that velocity indicates direction as well as speed. Demonstrate applications of speed and velocity using real world situations Analyze distance vs. time graphs in order to make predictions about the speed of the object based upon the slope. Construct distance vs. time graphs Calculate the average speed of an object based upon total distance over time. Define acceleration as increasing speed, decreasing speed, or a change in direction. Calculate the acceleration of an object using appropriate units Analyze the relationship between velocity and acceleration. Differentiate between acceleration and speed in terms of their unit labels. Combine velocities (in the same direction and in opposite directions) to calculate resultant velocity. Recognize that objects can travel at a constant speed and also be accelerating at the same time. Standards Addressed: CT Science Frameworks 8.1 An object s inertia causes it to continue to move the way it is moving unless acted upon by a force. 8.1 a - The motion of an object can be described by its position, direction, and speed. 8.1.a.1. An object is said to be in motion when its position changes in relation to a point of reference. An object s motion can be described and represented graphically according to its position, direction of motion, and speed. 8.1.a.2. Speed describes the change in an object s position over a period of time, and is measured in units Such as meters per second or miles per hour. Velocity takes into account an object s speed and the direction of its motion. 8.1.a.3. Average speed takes into account the different speeds at which an object moves over a period of time, Average speed is calculated by dividing the total distance traveled by the change in time, regardless of any changes in motion or direction during its travel 8.1.a.4. Motion of objects can be represented on a distance vs. time line graph, with distance traveled as the vertical ( y ) axis and time as the horizontal ( x ) axis. The slope (steepness) at any point of this line depends on the instantaneous speed of the moving object. A straight horizontal line indicates an object at rest. Core Scientific Inquiry, Literacy and Numeracy Standards C.INQ. 1-10 NGSS: Disciplinary Core Ideas PS2.A Forces and Motion Cross-Cutting Concept Scale, Proportion, and Quantity Revised 1/22/2016 Page 2 of 12
UNIT 2 - FORCES LEARNING GOALS Enduring Understanding(s): Forces affect the behavior of objects. Balanced forces keep objects at rest; unbalanced forces cause objects to move. A force is a push or pull and can be measured in Newtons. Essential Question(s): How do objects move? How do forces affect the motion of objects? Which factors affect the friction force between two surfaces; which factors affect the gravitational attraction between two objects? Content: Students will know Force is a push or pull. Gravity causes all objects to accelerate toward Earth at a rate of 9.8 m/s 2 Air resistance slows the acceleration of falling objects. An object falls at its terminal velocity when the upward force of air resistance equals the downward force of gravity. An object is in free fall if gravity is the only force acting on it. Objects in orbit appear to be weightless because they are in free fall. A centripetal force is needed to keep objects in circular motion. Gravity acts as a centripetal force to keep objects in orbit. Projectile motion is the curved path an object follows when thrown or propelled near the surface of Earth. Projectile motion has two components-horizontal motion and vertical motion. Gravity affects only the vertical motion of projectile motion. Newton s first law of motion states that the motion of an object will not change if no unbalanced forces on it. Objects at rest will not move unless acted upon by an unbalanced force. Objects in motion will continue to move at a constant speed and in a straight line unless acted upon by an unbalanced force Inertia is the tendency of matter to resist a change in motion. Mass is a measure of inertia. Balanced forces result in no motion; unbalanced forces result in motion. Skills Students will be able to Provide examples of how to change the motion of an object in different situations based upon knowledge of forces Determine the change in motion of an object and explain why the change occurs Given real world data, calculate force - Force = mass x acceleration (Newton) Explain and calculate how the mass of an object and force acting on it affect its acceleration Explain the effect of gravity and air resistance on various falling objects. Explain why objects in orbit are in free fall and appear to be weightless. Investigate and describe how projectile motion is affected by gravity. Describe Newton s first law of motion, and explain, using examples, how it relates to objects at rest and objects in motion. Calculate changes in motion of falling objects due to gravitational interactions (velocity: v = g x t) Revised 1/22/2016 Page 3 of 12
Represent the forces acting on an object in a force diagram Predict the motion of an object given the magnitude and direction of forces acting upon it Explain how friction affects the motion of objects Using examples, identify factors that affect friction Explain the difference between mass and weight Investigate and explain how unbalanced forces cause changes in motion (change in speed and/or direction) Standards Addressed: CT Science Frameworks 8.1 An object s inertia causes it to continue to move the way it is moving unless it is acted on by a force. 8.1.b. An unbalanced force acting on an object changes its speed and/or direction. 1. For an object s motion to change, a force must be applied over a distance. The change is motion due to this force is acceleration. Acceleration describes the change in an object s velocity over time. 2. Forces can act between objects that are in direct contact, or they can act over a distance. There are forces of attraction and forces of repulsion. Forces are measured in Newtons or pounds using scales or other instruments. 3. Forces act simultaneously on an object from all directions with different strengths (magnitudes.) The net force is the single resultant force when all the forces acting on an object are added together. If the net force is zero (forces are balanced), then the object will not accelerate. Objects accelerate due to an unbalanced net force. Balanced forces keep an object moving with the same velocity, including remaining at rest. 4. There is a proportional relationship between the mass of an object and the magnitude of the force needed to change its velocity. If a net force is applied to objects of different masses, then the object with the larger mass will have a smaller change in velocity. 5. The net force acting on an object can be determined by measuring its mass and change in velocity. 8.1.c. Objects moving in circles must experience force acting towards the center 1. Circular motion results when a net unbalanced force is constant in magnitude and always points toward the center of a circle. 2. Without a net center-pulling (centripetal) force, objects will continue to move in a straight line in a constant direction. 3. Objects in orbit around a larger body maintain their orbits due to the center-puling gravitational pull of the larger body. Core Scientific Inquiry, Literacy and Numeracy Standards C.INQ. 1-10 NGSS: Disciplinary Core Ideas PS2A: Forces and Motion Cross-Cutting Concepts Cause and Effect Revised 1/22/2016 Page 4 of 12
UNIT 3 - Motion II: Laws of Motion LEARNING GOALS Enduring Understanding(s): An object s motion can be predicted by natural laws Essential Question(s): How can motion be predicted? The relationships between the position of objects and their motion are governed by forces acting on the object. The factors which affect motion include force, mass and acceleration Content Students will know Newton s Second Law of Motion states that the acceleration of an object depends on its mass and on the force exerted on it. Newton s Second Law is represented by the following equations: F= m x a Newton s Third Law of Motion states that whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first object. Momentum is a property of moving objects. Momentum is calculated by multiplying the mass of an object by the object s velocity. When two or more objects collide, momentum may be transferred, but the total amount of momentum does not change. This is the law of conservation of momentum. Skills Students will be able to Using examples, explain how Newton s first law relates to objects at rest and objects in motion. Plan an investigation to provide evidence that the change in an objects motion depends upon the sum of the forces on the object and the mass of the object. Applying Newton s 2 nd Law of Motion, collect and graph data supporting the relationship between force, mass, and acceleration; provide a scientific explanation Calculate the force exerted by an object, in various situations, using the equation F = m x a Demonstrate Newton s third law of motion, and give examples of force pairs Given real world situations, make claims about interactions between and among objects and, using diagrams, identify the forces acting on those objects Calculate how momentum is conserved in real world situations using moving objects; apply the equation ᵖ = m x v Model examples that demonstrate the law of conservation of momentum Revised 1/22/2016 Page 5 of 12
Standards Addressed: CT Science Frameworks 8.1 An object s inertia causes it to continue to move the way it is moving unless it is acted on by a force. 8.1.a The motion of an object can be described by its position, direction of motion and speed. 8.1.b An unbalanced force acting on an object changes its speed and/or direction of motion. 1. For an object s motion to change, a force must be applied over a distance. The change in motion due to this force is acceleration. Acceleration describes the change in an object s velocity over time. 2. Forces can act between objects that are in direct contact, or they can act over a distance. There are forces of attraction and forces of repulsion. 3. Forces are measured in Newtons or pounds using scales or other instruments. 4. Forces act simultaneously on an object from all directions with different strengths (magnitudes). The net force is the single resultant force when all the forces acting on an object are added together. If the net force is zero (forces are balanced), then the object will not accelerate. Objects accelerate due to an unbalanced net force. Balanced forces keep an object moving with the same velocity, including remaining at rest. 5. There is a proportional relationship between the mass of an object and the magnitude of the force needed to change its velocity. If a net force is applied to objects of different masses, then the object with the larger mass will have a smaller change in velocity. 6. The net force acting on an object can be determined by measuring its mass and change in velocity. Core Scientific Inquiry, Literacy and Numeracy Standards C.INQ. 1-10 NGSS: Disciplinary Core Ideas PS2A: Forces and Motion Revised 1/22/2016 Page 6 of 12
UNIT 4 - Motion in Our Solar System LEARNING GOALS Enduring Understanding(s): The objects in the Solar System are in constant motion and that motion follows regular patterns. Gravity is the force responsible for the Solar System. Essential Question(s): How and why do objects move in our Solar System? How does the motion of the Earth, Sun and moon affect our physical world? Content: Students will know Solar System is a group of celestial bodies orbiting a central star, our Sun. Earth moves through space in two major ways: rotation and revolution. Earth has seasons because its axis is tilted as it revolves around the Sun. The strength of gravity between two objects depends on two factors: the masses of the objects and the distance between them. Inertia and gravity are two factors that keep the Earth in orbit around the Sun and the moon in orbit around the Earth. The changing relative positions of the moon, Earth, and Sun cause the phases of the moon, eclipses, and tides. Students will be able to Using a model, distinguish between rotation of Earth on its axis and its elliptical revolution around the sun. Use models to explain how Earth s rotation on its axis causes day and night. Make an Earth/Sun model to observe the effect of the tilt of Earth s axis on the daylight hours and seasonal temperatures at different locations on Earth. Design and conduct a scientific simulation to explore the relationship between the angle of the light source and the temperature on the surface it strikes. Use models and/or diagrams to explain the causes of the cycle of seasons on Earth. Explain the effect of gravity on orbits of planets and other objects in the solar system. Compare the revolution times of planets and relate them to distance from the Sun. Describe how the relative position of the Earth, moon and Sun affect phases, eclipses and tides. Use a model to demonstrate the phases of the moon relative to the position of the Sun, Earth and moon. Compare and contrast lunar eclipses and solar eclipses. Develop a model or illustration to show the relative positions of the Earth, Sun and moon during a lunar and solar eclipse and explain how those positions influence the view from Earth. Describe factors affecting tidal changes and analyze tidal change data for Long Island Sound. Standards Addressed: CT Science Frameworks 8.3 The Solar System is composed of planets and other objects that orbit the Sun. 8.3a Gravity is the force that governs the motion of objects in the Solar System 1. Earth is part of a system of celestial bodies that are grouped together around a central star, the Sun. This system includes objects of different masses and composition such as planets, moons, asteroids, minor planets and comets. These objects move in predictable paths determined by gravity. 2. Gravity is a force of attraction between two objects and the distance between them. The greater the total mass, the greater the force of gravity. The greater the distance between the two objects, the less the force Revised 1/22/2016 Page 7 of 12
of the gravity. 3. The difference between an object s mass and its weight is explained by gravity. Mass is the measure of the amount of matter in an object; weight is the force of gravity between an object and the celestial body it is on. Bodies in the Solar System have different masses; therefore the same object has a different weight on each celestial body. 4. Objects in the Solar System are held in their predictable paths by the center-pulling gravitational attraction of the very massive Sun. The interaction of the center-pulling force of gravity with a moving object s inertia (tendency to keep moving) keeps a less massive object (e.g. a planet, an asteroid or a moon) in circular motion (revolution) around a more massive object. 5. The Earth and other planets move through space in two ways; rotation on an axis and revolution around the sun. Earth revolves around the Sun in a near-circular path, explaining cyclical phenomena such as seasons and changes in visible star patterns (constellations). 6. Revolution period ( year ) depends on the speed at which an orbiting body is moving and the circumference of its orbit. Objects more distant from the sun s gravitational pull move slower than those that are closer. 8.3b The motion of Earth and the motion relative to the sun causes, daily, monthly and yearly cycle on Earth 1. Earth rotates around an axis or rotation, a line going through the center of the earth from the north pole to the south pole. The tilt of Earth s axis relative to its orbital path, combined with the spherical shape of the earth, cause differences in the amount of intensity of the Sun s light striking different latitudes of the earth. 2. Earth experiences seasons in northern and southern hemispheres due to the tilt of the Earth on its axis and the resulting angle of the sunlight striking Earth s surface at different points along its 365 day revolution period. Earth s tilt causes seasonal differences in the height of the perceived path of the Sun and the number of hours of sunlight. Seasons are not related to a change in distance between the Earth and the Sun, since that distance changes very little. Planets without a tilt of axis will experience no seasons in spite of the revolution. 3. Earth s moon is a natural satellite that revolves once around the earth in a period of about 27 days. The same half of the moon faces Earth throughout its revolution period. Phases of the moon as seen from Earth vary depending on the moon s position relative to the sun and the Earth, appearing as a full moon when the Sun and moon are on opposite sides of the earth and as a new moon when they are on the same side. 4. Eclipses occur when the moon, Earth and Sun occasionally align in specific ways. A solar eclipse occurs when the moon is directly between the earth and the Sun (during a new moon phase) and the moon blocks the Sun s light, creating a moving shadow on parts of the Earth. A lunar eclipse occurs when the Earth is directly between the moon and the Sun (full moon phase), the earth blocks the Sun s light, casting a shadow over the moon. 5. Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the moon, the sun and the rotation of the Earth. The times and amplitude of the tides are influenced by the alignment of the Sun and moon. Core Scientific Inquiry, Literacy and Numeracy Standards C.INQ. 1-10 NGSS: Disciplinary Core Ideas ESS1.B: Earth and the Solar System Revised 1/22/2016 Page 8 of 12
UNIT 5 - Work and Simple Machines LEARNING GOALS Enduring Understanding(s): Essential Question(s): In order for work to be done an object must move a distance. Simple machines can make work easier or more efficient by changing size, distance or direction of force. Work input and work output can be calculated to determine the efficiency of a machine. What is work? How do machines make doing work easier? How do force, distance, and direction affect the amount of work done by a machine? Content: Students will know Work is done when a force causes an object to move in the direction of the force. Work is calculated as force times distance. The unit of work is the newton-meter, or joule. Power is a measure of how fast work is done. Power is calculated as work divided by time. The unit for power is joule per second, or watt. A machine makes work easier by changing the size or direction (or both) of a force. A machine can increase force or distance, but not both. Mechanical advantage tells how many times a machine multiplies force. Mechanical efficiency is a comparison of a machine s work output with work input. Machines are not 100% efficient because some of the work done is used to overcome friction. In a first class lever, the fulcrum is between the force and the load. In a second class lever, the load is between the force and the fulcrum. In a third class lever, the force is between the fulcrum and the load. The mechanical advantage of an inclined plane is length divided by height. Wedges and screws are types of inclined planes. A wedge is a type of inclined plane. Its mechanical advantage is its length divided by its greatest thickness. The mechanical advantage of a wheel and axle is the radius of the wheel divided by the radius of the axle. Types of pulleys include fixed pulleys, movable pulleys, and block and tackles. Compound machines consist of two or more simple machines. Compound machines have lower mechanical advantage because they have more moving parts and therefore more friction to overcome. Skills Students will be able to Determine when work is being done on an object. Calculate the amount of work done on an object using the equation W = F x d Calculate the amount of power using the equation P = W t Explain the difference between work and power. Explain how a machine makes work easier. Describe and give examples of the force-distance trade-off that occurs when a machine is used. Calculate mechanical advantage using the equation MA = output force input force Test and Evaluate the efficiency of various simple machines. Explain why machines are not 100% efficient. Revised 1/22/2016 Page 9 of 12
Design and test simple machines in order to evaluate their usefulness for different tasks. Analyze the mechanical advantage provided by each simple machine. Identify the relationship simple machines to a compound machine. Standards Addressed: CT Science Frameworks 7.1 Energy provides the ability to do work and can exist in many forms. 7.1 a. Work is the process of making objects move through the application of force. 7.1.a.1. In order for an object to change motion, a push/pull (force) must be applied over a distance. 7.1.a.2. Work is a scientific concept that expresses the mathematical relationship between the amount of force needed to move an object and how far it moves. For work to be done, a force must be applied for a distance in the same direction as the motion. An object that does not move has no work done on it, even if forces are being applied. 7.1.a 3. Work (measured in joules) is calculated by multiplying for force (measured in Newtons) times the distance (measured in meters). When an object is lifted, the work done is the product of the force of gravity (weight) times the height of the object lifted. The amount of work done is increased if more force is applied or if the object is moved a greater distance. 7.1.a.4 Simple machines can be used to do work. People do input work on a simple machine which, in turn, does output work in moving an object. Simple machines are not used to change the amount of work to move or lift an object; rather, simple machines change the amount of effort, force and distance for the simple machine to move an object. 7.1.a.5 Simple machines work on the principle that a small force applied over a long distance is equivalent work to a large force applied over a short distance. 7.1.a.6. Some simple machines are used to move or lift an object over a greater output distance (snow shovel), or change direction of an object s motion, but most are used to reduce the amount of effort (input force) required to life or move an object (output force). 7.1.a.7. An inclined plane is a simple machine that reduces the effort force needed to raise an object to a given height. The effort force and distance and output force and distance depend on the length and height (steepness) of the inclined plane. 7.1.a.8. A pulley is a simple machine that reduces the effort force needed to life a heavy object by applying force through a greater distance (pulling more rope through the pulley). The effort force and distance, output force and distance and direction of motion all depend on the number of pulleys and their position. 7.1.a.9. A lever is a simple machine that reduces the effort force needed to lift a heavy object by applying the force at a greater distance from the fulcrum of the lever. The effort force and distance, output force and distance, and direction of motion all depend on the position of the fulcrum in relationship to the input and output forces. 7.1.a.10. The mechanical advantage of a simple machine indicates how useful the machine is for performing a given task by comparing the output force to the input force. The mechanical advantage is the number of times a machine multiplies the effort force. The longer the distance over which the effort force is applied, the greater the mechanical advantage of the machine. 7.1.a.11. The mechanical advantage of a machine can be calculated by dividing the resistance force by the effort force. Usually, the resistance force is the weight of the object in Newtons. 7.1.a.12. Simple machines always produce less work output than work put in because of some motion energy is converted to heat and sound energy by friction. Core Scientific Inquiry, Literacy and Numeracy Standards C.INQ. 1-10 NGSS: Disciplinary Core Ideas PS3:Energy Revised 1/22/2016 Page 10 of 12
UNIT 6 - Energy Transformations LEARNING GOALS Enduring Understanding(s): Energy in the world is dynamic, as it can be transferred and transformed. Energy can be stored in many forms and transformed into the energy of motion. Energy can change forms but is always conserved. Essential Question(s): How does the interaction between potential energy and kinetic energy affect matter in our daily lives? What is the role of energy in our world? How is energy converted from one form to another? Content: Students will know Energy is the ability to do work, and work equals the transfer of energy. Energy and work are expressed in units of joules. Kinetic energy is energy of motion and depends on speed and mass. Potential energy is energy of position. Gravitational potential energy depends on weight and height. Mechanical energy is the sum of kinetic energy and potential energy. Thermal energy and sound energy can be considered forms of kinetic energy. Chemical energy, electrical energy, and nuclear energy can be considered forms of potential energy. An energy conversion is a change from one form of energy to another. Any form of energy can be converted into any other form of energy. Kinetic energy is converted to potential energy when an object is moved against gravity. Elastic potential energy is another example of potential energy. Your body uses the food you eat to convert chemical energy into kinetic energy. Machines can transfer energy and can convert energy into a more useful form. Because of friction, some energy is always converted into thermal energy during an energy conversion. Energy is conserved within a closed system. According to the law of conservation of energy, energy cannot be created or destroyed. Perpetual motion is impossible because some of the energy put into a machine is converted into thermal energy because of friction. Skills Students will know and be able to: Explain the relationship between energy and work. Compare and contrast kinetic and potential energy. Describe how different types of stored (potential) energy can be used to make objects move. Calculate potential and kinetic energy and relate those quantities to total energy in a system. Use a diagram or model of a moving object (roller coaster, pendulum, etc.) to describe the conversion of potential energy into kinetic energy and vice versa Identify examples of different forms of energy and describe how they can be converted from one form to another for use by humans (e.g., thermal, electrical, light, chemical, mechanical). Explain how energy conversions make energy useful. Trace examples of energy conversions that occur in the human body. Revised 1/22/2016 Page 11 of 12
Explain the role of machines in energy conversions. Explain how energy is conserved within a closed system. Explain the law of conservation of energy. Give examples of how thermal energy is always a result of energy conversion. Investigate and explain why perpetual motion is impossible. Standards Addressed: CT Science Frameworks 7.1 Energy can exist in many forms. Energy provides the ability to do work. 7.1.b. Energy can be stored in many forms and can be transformed into the energy of motion 7.1.b.1. Energy is indirectly observed as the ability to exert pulls or pushes. 7.1.b.2. Potential energy is the capacity for doing work that a body possesses because of its position or condition. It is evident as gravitational 7.1.b.3. Kinetic energy is energy a body possesses because it is in motion. 7.1.b.4. Energy can be changed (transformed) from one form to another. For example, potential energy (carbohydrates in foods). 7.1.b.5. When energy is transformed, the total amount of energy stays constant (is conserved). 7.1.b.6. Work is done to lift an object, giving it gravitational potential energy (weight x height). The gravitational potential energy of an object moving down a hill is transformed into kinetic energy as it moves, reaching maximum kinetic energy at the bottom of the hill. 7.1.b.7. Some kinetic energy is always transformed into heat by friction; therefore, the object Will never reach the same height it started from again without added energy. Core Scientific Inquiry, Literacy and Numeracy Standards C.INQ. 1-10 NGSS: Disciplinary Core Ideas PS3:Energy Revised 1/22/2016 Page 12 of 12