AQA Physics paper 2

have magnitude and direction

force, velocity, momentum, acceleration

Only have magnitude and no direction

speed, distance, time

represented by an arrow - the length of the arrow shows the magnitude. The direction of the arrow shows the direction of the quantity

a push or pull on an object that is caused by it interacting with something

contact force

friction, air resistance, tension in ropes. etc

non contact force

magnetic force and gravitational force

• makes all things fall towards the ground

• gives everything a weight

The amount of material an object is made of It is the same value everywhere Measured using a mass balance

The force acting on an object due to gravity It depends on the strength of the gravitational field at the location of the object Measured using a calibrated spring balance - newtonmeter

Weight (N) = Mass (kg) x Gravitational Field Strength (N/kg) W=mg

mass

Diagrams that show all the forces acting on an object

The single force that replaces multiple forces acting at a single point

When a force moves an object through a distance, energy is transferred and work is done on the object

Work done (J) = Force (N) x Distance (m) W=Fs

1Nm

equilibrium

It may stretch, compress or bend

The object can go back to its original shape and length after the force has been removed

The object won't return to its original shape and length after the force has been removed

Force (N) = Spring Constant (N/m) x Extension (m) F=ke

The force applied F∝e

The point at which extension is no longer directly proportional to force

Momentum is the product of mass and velocity. Momentum is also a vector quantity – this means it has both a magnitude and an associated direction

Elastic potential energy (J) = 1/2 x Spring Constant (N/m) x extension^2 (m) Ee = 1/2Ke^2

It measures the distance and direction in a straight line from an object's starting point to its finishing point

Speed (how fast you're going) in a given direction

Distance Travelled (m) = Speed (m/s) x Time (s) s=vt

typical speed of a person walking 1.5m/s typical speed of a person running 3m/s Typical speed of a person cycling 6m/s what is the typical speed of a car 25m/s Typical speed of a train 55m/s Typical speed of a plane 250m/s

Fitness of the person Age of the person Distance travelled Terrain Climate Gender of the person

Temperature Atmospheric pressure Any large buildings or structures nearby e.g. forests reduce wind speed travelling through them

change in velocity in a certain amount of time

Acceleration (m/s²) = Change in Velocity (m/s) / Time (s) a=Δv/t

Negative acceleration - when something slows down, the change in velocity is negative

Uniform acceleration - acceleration due to gravity is uniform for objects in free fall

Final velocity² (m/s) - Initial velocity² (m/s) = 2 x Acceleration (m/s²) x Distance (m) v²-u²=2as

1. Gradient = speed

2. Flat sections = object is stationary

3. Straight uphill sections = object is travelling at a steady speed

4. Curves = object is accelerating or decelerating

5. Steepening curve = object is speeding up

6. Levelling off curve = object is slowing down

1. Gradient = acceleration

2. Flat sections = object is travelling at a steady speed

3. Uphill sections = object is accelerating

4. Downhill sections = object is decelerating

5. Curves = object is changing acceleration The steeper the graph, the greater the acceleration or deceleration

It causes objects to slow down when they rub against another surface

The resistance you get in a fluid Air resistance is a type of drag

Keep the shape of an object streamlined

1. When a falling object first sets off, the force of gravity is much more than the frictional force slowing it down, therefore the object accelerates

2. As the speed increases, the friction builds up

3. The acceleration is gradually reduced until eventually, the friction force is equal to the accelerating force - the resultant force is 0

4. At this point, it will have reached maximum speed or terminal velocity and will fall at a steady speed

The terminal velocity of any object is determined by its drag in comparison to its weight

• Because the drag had the same force on the parachuter as the weight

• weight pushes him down

• Drag/air resisance keeps him. Hes reached terminal velocity (2)

Inertia

If the resultant force on a stationary object is zero, the object will remain stationary If the resultant force on a moving object is zero, it will just carry on moving at the same velocity

Force ∝ Acceleration Acceleration is inversely proportional to the mass of an object

Resultant Force (N) = mass (Kg) x acceleration (M/s^2) F=ma

When two objects interact, the forces they exert on each other are equal and opposite An action always has an equal and opposite reaction

When you lean on a wall, you exert a force on the wall. Due to Newtons third Law, the wall also exerts an equal but opposite force back onto you.(1) You also exert a force on the ground and the ground exerts a force on you(1)The resultant force is zero, so you remain stationary (1)

Add masses to the trolley one at a time to increase the mass of the system 2)Record average acceleration for each mass To reduce the effect of friction use an air track.

1. Set up a trolley so it holds a piece of card that will interrupt the signal on the light gate twice.

2. This will measure acceleration.

3. Using a light measure the first and second point it passes. Work out an average acceleration. To reduce the effect of friction use an air track.

1. Keep total mass of the system the same but the change the mass on hook

2. Start with all the masses onto trolley

3. Transfer the hooks one at a time to the hook, to increase the accelerating force

4. The mass of the system stays the same as you're transferring the masses from one part of the system to another (the hook)

5. Record the average acceleration for each force To reduce the effect of friction use an air track.

How far the car travels during the driver's reaction time

The distance taken to stop under the braking force

The distance it takes for a car to stop in an emergency

Stopping Distance = Thinking Distance + Braking Distance

1. Speed - the faster you're going, the further you'll travel during your reaction time

2. Your reaction time - the longer it is, the longer your thinking distance

3. Alcohol

4. Drugs

5. Sleep deprivation

6. Distractions

1. Speed - the faster a vehicle travels, the longer it takes to stop

2. Weather/Road surface - if it's wet or icy, there is less grip (and less friction) between a vehicle's tyres and the road, which can cause tyres to skid

3. Condition of tyres - if the tyres are bald, then they cannot get rid of water in wet conditions, thus leading to skidding on top of the water

4. Quality of brakes - if brakes are worn or faulty, they won't be able to apply as much force as well-maintained brakes, which could be dangerous when wanting to brake hard

It has more energy in its kinetic energy stores, so the more work needs to be done to stop it - a greater braking force will be needed to make the vehicle stop within a certain distance, therefore the deceleration will be larger The larger the deceleration, the more dangerous it will be as the brakes could overheat or cause the vehicle to skid

The cyclist's reaction time increased (1) The thinking distance increased (1) Stopping distance is thinking distance plus braking distance (1)

The forces of the bike on the trailer and the trailer on the bike are equal in size and opposite in direction

in between 0.2 - 0.9

• Ruler drop test

• Computer based experiments

v^2 - u^2 = 2as v^2 = 2 x 9.8 x 0.162 + 0 = 3.1752 (1) v= √3.1752 = 1.781 m/s (1) a = Δv/t t = Δv / a = 1.781 / 9.8 = 0.181 s (1) = 0.18 (to s.f)

How much 'oomph' an object has All moving objects have it The momentum of one thing is always equal to the momentum of another thing e.g. a skateboarder has the same momentum as the skateboard

Momentum (kg m/s) = mass (kg) x velocity (m/s) p=mv

In a closed system, the total momentum before an event is the same as after the event

something that transfers energy from one place to another

The vibrations are perpendicular (at right angles) to the direction of energy transfer

• direction of energy transfer is sideways - but oscillations are up and down

• electromagnetic waves e.g light

• Ripples and waves in water

The oscillations are parallel to the direction of energy transfer

sound waves e.g ultrasound

Sound waves are longitudinal, in longitudinal waves the oscillations are parallel to the direction of energy transfer

Water waves are transverse. In transverse waves, the oscillations are perpendicular to the direction of energy transfer

Because light travels more slowly (in the glass block than in the air) so it changes direction

regions where the air particles are very close together

regions where the air particles are spaced out

wave speed (m/s) = frequency (H/z) x wavelength (m) V = f λ

The amplitude of a wave is the greatest distance a point on the wave moves from its undisturbed postion

The wavelength of a wave is the distance from a point on one way to the equivalent point on the adjacent wave

measure from one compression to the next compression or from one rarefaction to the next rarefaction

the number of waves passing a point each second 1 Hz = 1 wave per second

time (in seconds) for one wave to pass a point

period = 1/frequency (H/z)

330m/s

use signal generator attached to dipper of ripple tank - can create water waves at set frequency use strobe light to see wave crests on a screen below the tank increase frequency of strobe light until wave pattern on the screen appears to freeze and stop moving. Distance between each shadow line is equal to one wavelength Measure the distance between shadow lines that are 10 wavelength apart, then divide this distance by 10 to find the average wavelength use V = f λ

it allows you to measure a still pattern instead of a constantly moving one

• Turn on the signal generator and vibration transducer. String will start to vibrate

• Adjust the frequency of the signal generator until there's a clear wave on the string

• Measure the wavelength of these waves by measuring the lengths of 5 half wavelengths in one go, then divide to get the mean half wavelength, then double this to get a full wavelength

• Frequency of the wave is whatever the signal generator is set to

• use V = f λ to find the speed of the wave

• The wave is transmitted through the material - carries on travelling

• The wave is absorbed by the material

• The wave is reflected - 'sent back' - this is how echoes are produced

Angle of incidence = angle of reflection

The angle between the incoming wave and the normal

the angle between the refracted wave and the normal

An imaginary line that's perpendicular to the surface at the point of incidence

1m-10⁴m

10⁻²m

10⁻⁵m