Done in class Revised Assessed National 5 Physics Dynamics and Space Pupil notes I can describe vector and scalar quantities, and identify them. A scalar quantity has magnitude only A vector quantity has both magnitude and direction. Scalar quantities: speed, distance, mass, time, energy Vector quantities: velocity, displacement, weight, force, acceleration I can calculate the resultant of two vectors Vectors are added tip-to-tail The resultant vector is measured from the start of the first vector to the end of the last vector. All resultant vectors must have a three figure bearing, measured from 000 (North) 1
I can use a scale diagram or calculation to find a resultant displacement N (000 ) W (270 ) E (090 ) S (180 ) In the above example, the distance travelled is 19km, but to work out displacement, we use a scale drawing. Scale diagram drawing tips: Draw a mini compass. Choose a suitable scale- make it big enough to measure displacement accurately. Write this scale down. - e.g. 1cm:1km Measure your displacement bearing from where you started, not where you finish (common mistake). To avoid mistakes, quote bearings as a three figure-number. 2
I understand the difference between speed and velocity distance and speed are scalar quantities and require a magnitude only. where d = distance (measured in metres, m) v = speed (measured in metres per second, ms -1 ) t = time (measured in seconds, s) displacement and velocity are vector quantities and require both magnitude and direction. where s = displacement (measured in metres, m) and direction v = velocity (measured in metres per second, ms -1 ) and direction t = time (measured in seconds, s) 3
I know how to get information from velocity-time graphs Velocity (ms -1 ) Car is speeding up (accelerating) from O to A Car is going at a constant speed from A to B Car is slowing down (decelerating) from B to C Displacement = Area under velocity-time graph I can use the formula which links acceleration, change in speed and time, and calculate acceleration from a velocity-time graph. where a = acceleration (measured in metres per second squared, ms -2 ) v = final speed (measured in metres per second, ms -1 ) u = initial speed (measured in metres per second, ms -1 ) t = time (measured in seconds, s) 4
I know what is meant by a Force A Force can change the speed, direction or shape of an object. Force can be measured using a newton balance. Force is measured in Newtons (N). I know that friction is a type of force. Friction is caused by two objects moving while in contact with each other. The force of friction is always in the opposite direction to movement. Air resistance and drag are also types of frictional forces. I can describe some ways in which we can reduce frictional forces Streamlining Lubrication Smoothing surfaces 5
I know what is meant by balanced forces If two forces are the same size but act in opposite directions, they are known as balanced forces. I understand what Newton s 1 st law tells us about balanced forces and velocity If the forces on an object are balanced, then the object will either stay at rest (not move) or will move with a constant velocity in a straight line. I can calculate the unbalanced force if given two different forces in opposite directions I understand what Newton s 2 nd law tells us about unbalanced forces and acceleration. If the forces on an object are unbalanced, then there is more force acting in one direction than the other. The object will accelerate in the direction of the unbalanced force. 6
I can use the formula which links unbalanced force, mass and acceleration where F = unbalanced force (measured in Newtons, N) m = mass (measured in kilograms, kg) a = acceleration (measured in metres per second squared, ms -2 ) I can use the formula which links Work done, unbalanced force and distance where W = work done, or work energy (measured in Joules, J) F = unbalanced force (measured in Newtons, N) d = distance (measured in metres, m) 7
I know the difference between the mass of an object and its weight Mass is a measure of the amount of stuff that makes up an object, and is measured in kilograms. Weight is force acting downwards on an object caused by gravity, and is measured in Newtons. The weight of an object may be different on different bodies in our solar system, but the mass remains the same everywhere. I can use the formula which links weight, mass and gravitational field strength for different objects in our solar system where W = Weight (measured in Newtons, N) m = mass (measured in kilograms, kg) g = gravitational field strength (measured in Newtons per kilogram, Nkg -1 ) 8
I understand what Newton s 3 rd law tells us about action and reaction forces For every action (Force) there is an equal and opposite reaction (Force.) ] I understand Free fall and Terminal velocity in terms of Newton s laws and Friction. Free fall: Weight of a falling object acts downwards, but there is no reaction force acting upwards on the object, giving the sensation of weightlessness. Terminal velocity: An accelerating falling object will experience frictional forces which increase until balanced with the object s weight, which results in a constant speed called terminal velocity. Air Resistance acting upwards No reaction force on diver, so he feels weightless. When air resistance balances weight, terminal velocity is reached. 9 Weight acting downwards
I understand what is meant by projectile motion. A projectile is an object which is moving only under the influence of gravity, and falls to Earth with a curved path. Projectiles move with a constant horizontal velocity, but accelerate at the same time vertically. Notice how, after each second, the cannonball has travelled the same distance horizontally but travels a greater distance each second vertically. I can perform calculations involving projectile motion from a horizontal launch. From a horizontal launch: v = constant horizontally. u = 0 ms -1 vertically. a = 9.8 ms -2 vertically downwards. Top tip: split your page in two down the middle Horizontal Vertical one side for horizontal motion the other for vertical motion. d = 100m v = 10 ms -1 a = 9.8 ms -1 v =? 10 t =? u = 0 ms -1 t =?
I can explain the orbit of a satellite in terms of projectile motion A satellite, after launch, will begin to fall towards earth with a curved path, just like any projectile. If launched with enough velocity, the curved path will extend beyond the curvature of the earth, and the satellite will continue to follow that curved path around the earth. This is how a satellite stays in orbit. I can describe some of the risks and benefits of space exploration Risks Re-entry to a planet s atmosphere is challenging because It creates a large amount of heat due to air resistance. Thermal protection systems must be used to ensure the spacecraft is protected on re-entry. The angle of re-entry must be precisely calculated so the spacecraft doesn t bounce off the atmosphere. Benefits Space exploration has helped to develop The accuracy of weather forecasting Telecommunications via Satellites Analysis of our environment National security Sat-Nav systems Robotics 11
I can discuss the impact that space exploration has had on our understanding of the universe and of planet Earth Space telescopes (e.g. Hubble), Space probes (e.g. Voyager) and Space rovers (e.g. Spirit) have all contributed to our understanding of the universe in different ways. For example: Hubble s deep field lens allows us to capture images across many wavelengths of EM radiation from deep space. Voyager has performed fly pasts of many objects in our solar system giving up close, detailed images never seen before. Spirit analysed the terrain on Mars to help determine if life had ever existed there. I know that large distances in space are measured in light years. A light year is the distance that light will travel in one year: One light year = 9.5 x10 15 metres. Our solar system measures only a small fraction of a light year, yet the universe measures many billions of light years. 12
I know what is meant by the observable universe and what it tells us about the origin and age of the universe Since light travels at a finite speed, it takes some time to get to us. If an object is far enough away, its light may not have reached us yet. The furthest point that we can see is the distance which light must have travelled for the whole age of the universe. This distance is called the observable universe. This means that we can calculate the age of the universe- estimated to be just less than 14 billion years old. The universe is constantly expanding- objects are getting further apart. This suggests that all matter in the universe has all been expanding from a single point- an expansion started by the big bang. I know that different objects in the universe can be detected using different parts of the electromagnetic spectrum. Some objects in the universe cannot be detected using visible light, and look dark when viewed with optical telescopes. However, these objects often emit radiation in the form of Infrared, Ultraviolet, X-rays or gamma rays, which can be detected by using specialised telescopes. 13
I can identify a continuous spectrum and a line spectrum White light sources, when split up using a prism or viewed through a spectroscope will produce a continuous spectrum of colours (ROY G BIV). Other light sources (such as fluorescent strip lamps) will instead produce a line spectrum when viewed through a spectroscope, where not all the colours are present. NB: One of these is called a spectrum and more than one of these are called spectra. I can use line spectra to identify the elements present in stars Different elements emit different wavelengths (colours) of light depending on their atomic structure. These act as an atomic fingerprint that can identify the element. Looking at light coming from a star using a spectroscope will identify the elements in that star. The line spectrum for Hydrogen 14