Physics P3 Ocr Gateway B

Front 1

What is the equation for distance?

Back 1

Distance = speed / time

Front 2

What is the equaion for average speed?

Back 2

Average speed = (u + v) / 2

Front 3

Distance time graphs
a) What does the gradient represent?
b) What do flat sections represent?
c) A steeper gradient means what?
d) Curves represent what?
e) A "downhil" section means what?

Back 3

a) Speed
b) The vehicle has stopped
c) A faster speed
d) Acceleration/deceleration
e) It's changed direction and is coming back to its starting point

Front 4

How do you calculate speed from a distance time graph?

Back 4

Using the gradient (y/x)

Front 5

What is acceleration?

Back 5

How quickly the speed is changing

You can also accelerate when changing direction, with or without changing speed

Front 6

What is the equation for acceleration?

Back 6

Acceleration = change in speed / time taken

Front 7

Speed time graphs
a) What does the gradient represent?
b) What do flat parts of the graph represent?
c) What does a steeper gradient mean?
d) What do uphill and downhill sections mean?
e) What does a curve mean?

Back 7

a) Acceleration
b) Steady speed
c) Greater acceleration/deceleration
d) Uphill = acceleration Downhill = deceleration
e) Non-uniform (changing) acceleration/deceleration

Front 8

How do you work out the distance travelled from a speed time graph?

Back 8

The area under the graph

Eg Triangle = (bxh) / 2

Front 9

What is the difference between mass and weight?

Back 9

Mass = a measure of how much matter is in an object
Weight = caused by the pull of gravity and is a force

Front 10

What is the equation for weight?

Back 10

weight = mass x gravitational field strength

Front 11

What are the 6 different types of forces?

Back 11

1. Gravity or weight = always downwards
2. Reaction force from a surface = usually upwards
3. Thrust/push/pull due to an engine/rocket speeding something up
4. Drag/air resistance/friction = slowing something down
5. Lift due to a plane wing
6. Tension in a rope/cable

Front 12

How must the forces be in order for an object to be stationary?

Back 12

Balanced
Force of gravity acts down
Causes a reaction force from the surface, pushing up

Front 13

How must the forces be in order for a steady horizontal speed?

Back 13

Balanced
Force of gravity/weight acts down
Reaction force from surface, pushing up
Thrust
Drag/air resistance

Front 14

How must the forces be in order for horizontal acceleration?

Back 14

Unbalanced
A larger thrust than air resistance/drag
(Gravity and reaction force are still balanced)

Front 15

How must forces be in order for a steady vertical speed?

Back 15

Balanced
Weight acts downwards
Air resistance/drag upwards

Eg. skydiver

Front 16

How much forces be in order for vertical acceleration

Back 16

Unabalanced
Force of weight bigger than drag/air resistance

Front 17

What is the equation for force?

Back 17

Force = mass x acceleration

Front 18

What is the equation for stopping distance?

Back 18

Stopping distance = thinking distance + braking distance

Front 19

What is thinking distance defined as?

Back 19

The distance the car travels in the time between the driver noticing the need to brake and applying the brakes

Front 20

What factors affect thinking distance

Back 20

Speed: Faster speed = further distance
Tiredness
Drugs and alcohol
Distractions
A Lack of concentration

Front 21

What is braking distance define as?

Back 21

The distance taken to stop once the brakes have been apllied

Front 22

What factors affect braking distance?

Back 22

1) Speed: Faster speed = further distance
2) Mass: Heavier vehicale = longer takes to stop
3) Brake quality = if worn or fault won't be able to brake with as much force
4) Grip = icy/wet conditions and tyre treads

Front 23

What is the relationship between speed and thinking distance? Why is this?

Back 23

- Linear =Thinking distance increases at the same rate as speed
- Thinking time stays constant but the more distance you cover in that time if speed is greater

Front 24

What is the relationship between speed and braking distance?

Back 24

A squared relationship = As speed doubles, braking distance quadruples

Front 25

Why is speed and braking distance a squared relationship?

Back 25

Kinetic energy Transferred = Work done by brakes
1/2 x M x V(2) = F x d (d = braking distance, f = braking force)

'F' is always the maximum possible braking force, d must increase to make the equation balance/to convert the extra KE

Front 26

What is the equation for momentum? (kgm/s)

Back 26

Momentum (kgm/s) = Mass (kg) x Velocity (m/s)

Front 27

How can you use Newton's 2nd law of motion to explain that when a force acts, it causes a change in momentum?

Back 27

Force = mass x acceleration
1) Any force applied increases it acceleration
2) Acceleration is change in velocity over time
3) A change in momentum can be caused by a change in velocity so any force applied to an object over time causes a change in momentum

Front 28

When is work done?

Back 28

Whenever a force moves an object in a certain distance

Front 29

What is the equation for work done?

Back 29

Work (J) = force (N) x ditance moved in direction of force (m)

Front 30

Explain how seatbelts protect the occupant

Back 30

- The seatbelt will stretch a little once locked and allow to stop more slowly. In stretching, the seatbelts absorb kinetic energy and convert it to elastic energy, reducing injuries.
- Reduces rate of change of momentum F= change in momentum/time

Front 31

Explain how crumple zones protect the occupant

Back 31

- They change shape on impact at the front and back of the car. By changing shape they absorb energy and increase the time between impact and stopping
- Reduces rate of change of momentum F= change in momentum/time

Front 32

Explain how airbags protect the occupant

Back 32

- They inflate on impact and slow passengers down more slowly. It prevents them hitting the dash-board/steering wheel. They absorb some kinetic energy, reducing the injuries
- Slow passenger down

Front 33

Explain how crash barriers protect the occupant

Back 33

They are made from a material that changes shape on impact so the car travels further before stopping

Front 34

Explain how roll cages protect the occupant

Back 34

Rigid frame inside the car. Prevents the car from collapsing and crushing the occupants in a roll crash

Front 35

Explain how traction control prevents accidents

Back 35

Stops wheels from spinning when accelerating quickly. Gives maximum grip and stability during acceleration

Front 36

Explain how brakes prevent accidents

Back 36

The brakes get hot and transfer some of the cars kinetic energy, slowing down the car

Front 37

Explain how an escape lane prevents accidents

Back 37

They are often on steep hills and allow vehicles that have failed brakes to stop by slowly by running into an upward slope with a rough surface

Front 38

Explain how ABS prevents accidents

Back 38

- Gives vehicle stability and allows driver to maintain steering during hard braking in slippery conditions
- Driver must press the pedal fully
- Wheel speed sensors send information to computer about rotational speed
- Computer uses information to control pressure to the brakes and applies the amount to prevent the wheels from locking up
- Brakes pump on and off
- Driver gets maximum braking force without skiiding and can still steer the car. The car can stop in a shorter distance but not necessarily quicker

Front 39

What causes injuries in a vehicle collision?

Back 39

When there is a sudden change in momentum and a large force is exerted which causes rapid acceleration of body parts

Front 40

How are safety features tested?

Back 40

- Crashing cars containting dummies both with and without the safety features and watching slow motion film to see the results
- The dummies have sensors at different places to show where a real person would be injured and it's severity
- Repeat tests and different cars, speeds and sized dummies
- Results are compared to real data on deaths/severe injuries to see if there is a benefit

Front 41

What is gravitational potentional energy?

Back 41

The energy that something has because of its heigh above ground. The energy uses to raise it is "stored" and can be changed to KE if it falls

Front 42

What is the equation for gravitational potential energy?

Back 42

GPE = mass x gravitational field strength x height

Front 43

What is kinetic energy?

Back 43

The energy something has when moving

Front 44

What does the kinetic energy of something depend on? Why?

Back 44

Speed
Mass

Greater mass/speed = more KE

Front 45

What is the equation for kinetic energy?

Back 45

KE = 1/2 x mass x speed (squared)

Front 46

What happens when something falls?

Back 46

Its gravitational potential energy is converted into kinetic energy
The further it falls, the faster it goes
KE gained = GPE lost

Front 47

What happens to a falling objects speed/KE reaches terminal speed?

Back 47

Speed cannot increase, so KE doesn't increase
The GPE is transferred to internal energy of the object or is used in heating up the air particles through friction

Front 48

How do you work out the height that something needs to fall from to reach a certain speed?

Back 48

h= v (squared) + 2 x gravitational field strength

Front 49

Explain energy transfer in a rollercoaster

Back 49

At top = lots of GPE
Descends = GPE transferred to KE = speeds up
At bottom of drop = minimum GPE, maximum KE

Front 50

What is power?

Back 50

How quickly work is done

Front 51

What is the equation for power?

Back 51

Power (W) = Work done (J)
Time (s)

Front 52

Prove that Power = Force x Speed

Back 52

Work done = Force x distance
Speed = Distance / Time
Workdone = Force x speed x time /time
Cancel out time
Combining = Force x Speed

Front 53

Why do larger, more powerful engines usually have a high fuel consumption?

Back 53

They transfer more energy from its fuel every second

Front 54

What is fuel consumption often given in?

Back 54

Miles per gallon (mpg)
Litres per 100km (l/100km)

Front 55

What 6 things effect fuel consumption?

Back 55

Engine size
Mass of car
Driving style (faster accelerations/harder braking)
Speed
Road conditions
Shape of car (Roof box = increases air resistance)

Front 56

What 3 emissions are released when cars burn fuel?

Back 56

Carbon dioxide, Nitrogen dioxide and water vapour

Front 57

What environmental problems can car emissions cause?

Back 57

Acid rain and global warming

Front 58

What are two alternative fuel sources for cars?

Back 58

Electricity
Biofuels

Front 59

What advantages does running cars on biofuel have?

Back 59

Made from plants/organic waste = renewable = won't run out
Doesn't produce much pollution at the point of use
No overall increase in carbon dioxide (plants take in CO2 and produce it when burnt)

Front 60

What advantage does running cars on electric have?

Back 60

Doesn't release energy at the point of us

Front 61

What disadvantages do electric cars have?

Back 61

- Electricity comes from power stations that burn fossil fuels
- Expensive to make and buy
- Limited performance compared to fossil fuels

Front 62

What is one way around using power stations to produce electricity as a fuel for cars?

Back 62

Using solar panels to change energy from the sun into electricity to power the motor

Front 63

P3

Back 63

P3