Give some examples of a Noncontact force

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1 What is a vector quantity? What is a scalar quantity? What do physicists mean by the term displacement? State Newton s third law of motion. What is the unit of Force What is meant by the term Contact force Give some examples of a Noncontact force What is meant by the term Resultant force What will be the effect on an object when the resultant force is zero? What will be the effect on a object with a resultant force of more than zero? What does a Free-body force diagram show State what a Moment (of the force) is.

2 A scalar quantity has magnitude but no direction. Eg, speed, distance, time, mass, energy and power A vector quantity is a physical quantity which has magnitude and direction. Eg, velocity, acceleration, force, momentum and weight Newtons third law of motion sates that when two objects interact with each other, they exert equal and opposite forces on each other. Displacement is distance in a given direction. It may be much shorter than the actual distance something has moved A contact force is a force that acts on objects only when the objects touch each other. Eg friction, air resistance, stretching forces The unit of force is the newton (N) The resultant force is a single force that has the same effect as all the forces acting on an object Non contact forces include magnetic force, electrostatic force and the force of gravity. When the resultant force is greater than zero, the speed or direction of an object will change. When the resultant force is zero, an object stays at rest or at the same speed or direction. A moment of a force is a measure of the turning effect of the force on an object. A free-body force diagram of an object shows the forces acting on it.

3 What is the equation that links Moment, Force and Distance. Why can levers described as Force Multipliers? State what the Centre of Mass of an object is Where will the centre of mass settle in a suspended object Where will the centre of mass be located in a symmetrical object? State the principle of moments If an object at rest doesn t turn what can you say about the moments? What determines whether a moment will be clockwise or anticlockwise? (Separate physics) What is the parallelogram of forces? Why is a parallelogram of forces helpful? What can we say about the resultant force when an object is in equilibrium? State the equation that links Distance Travelled, Speed and Time.

4 They increase the distance from the pivot to enable a bigger load to be lifted with the same effort M = Fd M = Moment (Nm), F = Force (N), d= distance (m) The object will come to rest with its centre of mass directly below the point of suspension The centre of mass of an object is the point where most of its mass can be thought of as being concentrated. The principle of moments states that:- the sum of all the clockwise moments around any point equals the sum of all the anticlockwise moments around any point. In a symmetrical object, the centre of mass will be at the point where the axes of symmetry meet. The direction of the force and the position of the fixed point determines whether the moment acts clockwise or anticlockwise. If an object at rest doesn t turn, the sum of the anticlockwise moments about any point equals the sum of the clockwise moments about that point. The parallelogram of forces can be used to find the resultant force when two forces are exerted which are not acting along the same line. The parallelogram of forces is a scale diagram of two vectors. s = vt s = Distance travelled (m), v = Speed (m/s), t = Time (s) When an object is in equilibrium, the resultant force Is zero.

5 On a distance-time graph, how is a stationary object represented? On a distance-time graph, how is an object moving at constant speed represented? What does the gradient of the line on a distance-time graph represent Why is velocity a vector quantity? Write the equation that links Acceleration, Change in velocity and Time taken. What is meant by the term deceleration? What does the gradient of the line on a velocity-time graph represent? What does a horizontal line on a velocity-time graph represent? How are acceleration and deceleration represented on a velocity-time graph How would you obtain a value for speed of an object at a specific moment from a distance-time graph. How could you determine the distance travelled from a velocitytime graph What is the relationship between mass of an object and its acceleration for a given force?

6 An object moving at constant speed is represented by a line which slopes upwards. A stationary object is represented by a horizontal line. Velocity has both magnitude and direction and is therefore a vector quantity. Speed has scale only as is a scalar quantity. Deceleration is the change of velocity per second when an object slows down. The gradient of a distance-time graph represents an objects speed. a = v t a = Acceleration (m/s 2 ), v -= Change in velocity (m/s), t = Time taken for change (s) A horizontal line on a velocity-time graph represents zero acceleration. The gradient of the line on a velocity-time graph represent acceleration. On a velocity-time graph, the area under the line represents the distance travelled. On a velocity-time graph, acceleration is represented by a positive gradient and deceleration is represented by a negative gradient. The greater the mass of an object, the smaller its acceleration for a given force. The speed of an object at a specific moment of time is given by the gradient of the tangent to the line on a distance-time graph v

7 What do physicists mean by the term Inertia? State Newton s second Law of Motion Write the equation that links Resultant force, mass and acceleration Explain the difference between Mass and Weight What is meant by the term Terminal velocity? What value does the resultant force on an object have when the object is moving at terminal velocity? The Stopping Distance of a vehicle is made up of which two distances? What is the Conservation of Momentum in a closed system Write the equation that links Momentum (of a moving object), Mass and Velocity. What is the unit of Momentum Why is Momentum (mass x velocity) called a Vector quantity? What is the purpose of crumple zones and seat belts in vehicles?

8 The acceleration of an object is proportional to the resultant force on an object, and inversely proportional to the mass of an object. Mass is the quantity of matter in an object. The Weight of an object is the force acting on the object due to gravity The Inertia of an object is its tendency to stay at rest or in uniform motion F = ma F = Resultant force (N), m = Mass (kg), a = Acceleration (m/s 2 ) When an object is moving at terminal velocity, the resultant force on it is zero. The terminal velocity of an object is the velocity it eventually reaches when it is falling. The weight of the object is then equal to the frictional force on the object According to the conservation of momentum, the total momentum before an event is the same as the total momentum after the event The Stopping distance of a vehicle is made up of the Thinking distance and the Braking distance The unit of Momentum is kg m/s p = mv p = Momentum (kg m/s), m = Mass (kg), v = Velocity (m/s) Crumple zones increase the impact time in a collision thus reducing the impact force. Momentum is a quantity with both size and direction and is therefore a vector quantity.

9 An object can be called elastic if it State Hooke s Law Write the equation that links Force (applied to a spring), the Spring constant and the extension of the spring. What is the unit of Pressure? Write the equation that links Pressure, Force and Area What is the effect of increasing depth on pressure in a liquid? How does the density of a liquid affect the pressure in a liquid. Write the equation that you could use to calculate the pressure of a liquid in a column. Why does atmospheric pressure decrease at higher altitude? What two things does the pressure at any point in a fluid depend upon? What do physicists mean by the term Upthrust What will happen to an object if it s weight is greater than the upthrust exerted on it?

10 The extension of a spring is directly proportional to the force applied, as long as it s limit of proportionality Is not exceeded. An object is called elastic if it returns to its original shape after removing the force deforming it. The unit of pressure is Pascal (Pa) 1 Pa = 1 N/m 2 F = ke F = Force applied (N), k Spring constant (N/m), e = Extension (m) The pressure in a liquid increases with increasing depth p = h x x g p = Pressure (Pa), h = Height (m), = density (kg/m 3 ), g = Gravitational field strength (N/kg) The pressure at a point in a fluid depends on the density of the fluid and the depth of the fluid at that point. p = F A p = Pressure (Pa), F = Force (N), A = Area (m 2 ) The greater the density of a liquid, the greater the pressure in the liquid Atmospheric pressure decreases with higher altitude because there is less air above a given altitude than there is at a lower altitude. An object will sink if it s weight is greater than the upthrust on it when it is fully immersed Upthrust is the upward force that acts on a body (eg by water)

11 Name the two types of waves you ve studied in physics What is the relationship between direction of oscillation and direction of energy transfer in Transverse waves? What is the relationship between direction of oscillation and direction of energy transfer in Longitudinal waves? Sound Waves are an example of what kind of wave? Electromagnetic waves are examples of which type of wave? Define the Frequency of a wave and name the unit Write the equation which links Wave speed, Frequency and Wavelength What is the Wavelength of a wave? What is the Amplitude of a wave Why do rays get Refracted at the boundary between different materials What can you say about the angle of reflection compared to the angle of incidence of a wave Why can t sound waves travel through a vacuum?

12 Transverse waves oscillate perpendicular to the direction of energy transfer of the wave Transverse waves and Longitudinal waves Sound Waves are Longitudinal waves Longitudinal waves oscillate parallel to the direction of energy transfer of the waves. For any wave, it s frequency is the number of waves passing appoint per second. Unit is Hertz (Hz) Electromagnetic waves are transverse waves. For any wave, its wavelength is the distance from a point on the wave to the equivalent point on the next wave ( eg from one trough to the next) v = f x λ v Wave speed (M/s), f = Frequency (Hz), = Wavelength (m) Refraction occurs at a boundary between two different materials because the speed (and therefore wavelength) Changes at the boundary. Amplitude is the maximum displacement of a point on the wave from its undisturbed position. Eg depth of wave trough from the position of rest. Sound waves are vibrations that travel through the particles of a medium. Therefore they cannot travel through a vacuum. The angle of reflection will be the same as the angle of incidence because their speed and wavelength do not change on reflection

13 What happens to the pitch of a note if the frequency of the sound wave increases? What happens to the loudness of a note if the amplitude of a sound wave increases? Above what frequency are sound waves classified as Ultrasound? Why is an Ultrasound scan safer than an X-ray? What is a Seismic wave? What kinds of waves are P-waves and S-waves? List the names of the wave components of the electromagnetic spectrum Can electromagnetic waves transport energy, matter or energy and matter? White light contains which colours? Give an example of a use for Infrared radiation Give an example of a use for Microwave radiation. Which electromagnetic wave is used to carry radio and TV broadcasting?

14 If the amplitude of a sound wave increases, the note will become louder. The pitch of a note increases if the frequency of the sound wave increases. Ultrasound scans are non-ionising, so they are safer than X-rays which are ionising. Ultrasound waves are sound waves of frequency above 20kHz Primary (P-waves) are longitudinal waves. Secondary (S-waves) are transverse waves A seismic wave is one which travels through the earth. They are produced by an earthquake and spread out from the epicenter. Electromagnetic waves are electric and magnetic disturbances. They can transport energy but not matter. Radio (Longest, Lowest frequency), Microwaves, Infrared, Visible Light, Ultraviolet radiation, X-rays, Gamma radiation Infrared radiation is used for carrying signals from remote control handsets and inside optical fibres. White light contains all the colours of the visible spectrum. Radio waves. Microwave radiation is used to carry satellite TV programmes and mobile phone calls.

15 Why is Infrared radiation harmful to people? What is an Optical fibre What is the name given to a wave which carries information by varying their amplitude? Which part of the electromagnetic spectrum is used in hospitals to make images of bone? Identify some uses for Gamma radiation Why do X-rays and Gamma rays damage living cells. What happens to an atom when it becomes Ionised The Law of Reflection states that the Line of reflection equals the.. When reflecting a light ray using a plane mirror where would you measure the angle of incidence using a protractor. Explain the difference between Specular and Diffuse radiation. Describe what is meant by Refraction of waves How will a ray be refracted when it travels from air into glass?

16 Optical fibres are very thin transparent fibres that are used to transmit communication signals by light and infrared radiation. Infrared radiation can cause skin burns ( sunburn ) X-rays are used in hospitals to produce X-ray images. They are absorbed by bones more than by soft tissue. Carrier Waves carry information by varying their amplitude. X-rays and Gamma rays cause ionisation in living cells which might cause gene mutation or kill the cell. Gamma rays are used to kill harmful bacteria in food and sterilize surgical equipment. They are also used to kill cancer cells. The Line of Reflection = The Line of Incidence When an atom is ionised, electrons get knocked off it and the atom becomes charged. Specular reflection is reflection in a single direction without scattering (eg a smooth mirror). Diffuse radiation is reflection from a rough surface that scatters the light The angle of incidence is measured between the incident (incoming) ray and the normal line (drawn perpendicular to the mirror). When a ray travels from sir into glass it will be refracted toward the normal line. The angle of refraction is less than the angle of incidence. Refraction is the change in direction of waves when they travel across a boundary from one medium to another

17 Describe how the wavelength ( ) of light changes from violet to red. Why does a white piece of paper appear as white in daylight? What could you say about the pigments on the surface of a book cover which appears red. If I looked at a red book under blue light, what colour would the book appear to be? What will be the effect of a convex lens on parallel rays? What will be the effect of a concave lens on parallel rays? Write the equation that links Magnification, Image height and Object height. (Also for Biology) What does a Ray Diagram show? How are the magnetic field lines arranged around a bar magnet? What will happen if two north poles are brought together? What do physicists mean by the term Induced Magnetism Why is steel used instead of iron to make permanent magnets?

18 The surface of the paper has no pigments, so reflects all the wavelengths of light The wavelength ( ) of light increases from violet to red across the visible spectrum The book would appear to be black as it would absorb all of the incident light The book surface that appears red will contain pigments which absorb all the colours of White light except red. The red light is reflected A concave lens will make parallel rays spread out as if they had come from a point called the principle focus. A convex lens will focus parallel rays to a point called the principal focus. A ray diagram can be drawn to find the position and nature (virtual or real) of an image formed by a lens. Magnification = Image Height Object Height Two north poles will repel because like poles repel and unlike poles attract. The magnetic field lines curve around from the North Pole to the South Pole Steel doesn t lose its magnetism as easily as Iron, so is better for permanent magnets. Induced magnetism is magnetism created in an unmagnetised magnetic material when the material is placed in a magnetic field.

19 When an electric current is passed along a wire, what gets set up around the wire? A long coil of wire that produces a magnetic field in and around the coil when there is current in the coil is called a.. What happens to the magnetic field in a solenoid when the current is increased? How would you decrease the magnetic field in a solenoid? What would be the effect of reversing the direction of the current on the magnetic field lines of a solenoid? When a current is passed through a wire in a magnetic field a force is exerted. This is known as the In the motor effect, how can the direction of the force be reversed? What happens to the coil in an electric motor when a current is passed through it? A solenoid which has an iron core is commonly referred to as an In the motor effect, how can the size of the force be increased? What rule is used to identify the direction of the force relative to the current and magnetic field lines What does Magnetic Flux Density measure?

20 Solenoid When an electric current passes along a wire, a magnetic field is set up around the wire. Decrease the current. When the current is increased in a solenoid, the magnetic field increases. Electromagnet. (A solenoid with a magnetic core) Reversing the direction of the current would reverse the direction of the magnetic field lines. The size of the force can be increased by Increasing the current, or, Increase the strength of the magnetic field, or, Increasing the length of the conductor Motor Effect Flemings Left Hand rule Reversing the direction of the current or the magnetic field will reverse the direction of the force Magnetic Flux Density is the measure of the strength of the magnetic field. When a current is passed through a electric motor, the coil turns.

21 What is the equation that links Force, Magnetic Flux Density, Current and Length? (Be able to select from the given data sheet) What is the generator effect? ) What is a simple alternating current made from? A dynamo is an example of a direct current generator. How does a d.c generator differ from an a.c generator What are transformers used for? What type of transformer is used to increase the size of alternating potential difference? Why does a transformer only work with an a.c current? A transformer is comprised of What was formed from gas and dust clouds that became increasingly concentrated because of gravitational attraction? What is a Protostar (Separate Science) Stars can remain in their Main sequence for millions of years. How do they maintain their energy output? What enables a star (eg The Sun) to be stable?

22 The generator effect is the effect of inducing a potential difference using a magnetic field. F = B x I x L F = Force (N), B = Magnetic Flux Density (tesla T), I = Current (A), L = Length (m) A direct current generator has a splitring instead of two slip rings. A simple alternating current generator is made up of a coil that spins in a uniform magnetic field. A Step-up Transformer is used to increase the size of the alternating potential difference. Transformers are used to increase or decrease the size of an alternating potential difference. A transformer is comprised of a primary coil, a secondary coil and an iron core. A transformer only works with a.c current because a changing magnetic field is necessary to induce a.c in the secondary coil. A Protostar (Star-to-be) is a concentration of gas and dust that becomes hot enough to cause nuclear fusion The Solar System Stars are stable when the gravitational forces acting inwards balance the forces of nuclear fusion in the core acting outwards. Hydrogen nuclei fusing together to form helium nuclei release vast amounts of evergy. This continues until there are no hydrogen nuclei left

23 State the lifecycle of a star with about the same mass as the sun State the lifecycle of a star with much more mass than the sun What will the Sun become in the final stage of its life-cycle What is a Supernova? What causes a planet to continue moving along its orbit? In which direction does the force of gravity act in a circular orbit? How does the velocity of a body in circular orbit change during the orbit. (Separate Science) According to the theory, what was the Big Bang The stretching of light waves from a star or galaxy moving away is called.? Electromagnetic radiation which was created just after the Big Bang is called.? What evidence do scientists use to support the Big Bang theory?

24 Protostar -> Main sequence star - >Red supergiant ->Supernova - >Neutron star (or Black hole if big enough mass) Protostar > Main sequence star > Red giant > White dwarf > Black dwarf A Supernova is the explosion of a Red supergiant after it collapses. The Sun will eventually become a Black dwarf. The force of gravity on an orbiting body in a circular orbit is toward the centre of the circle. The force of gravity between a planet and the Sun keeps the planet moving along its orbit. Red Shift. The wavelength is increased thus light is shifted toward the red end of the spectrum. As a body moves around a circular orbit, the magnitude of its velocity (its speed) doesn t change. The direction of velocity constantly changes and is always at right angles of the direction of the force Cosmic Microwave Background Radiation (CMBR) The Big Bang theory suggests that the universe started by a massive explosion form a very small point. Red shift provide evidence that the universe is continually expanding. The presence of CBMR can only be explained by the Big Bang theory.