Simplified P3 - Work and Power, Energy on the move, Crumple Zones Flashcards Preview

Phy: P1-P3 OCR > Simplified P3 - Work and Power, Energy on the move, Crumple Zones > Flashcards

Flashcards in Simplified P3 - Work and Power, Energy on the move, Crumple Zones Deck (26)
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1
Q

When is work done?

A

Work is done when a force moves an object in the direction in which the force acts.

2
Q

What is weight?

A

Weight is a measure of gravitational attraction on a body acting towards the centre of the Earth.
1 kg mass has a weight of 10n on earth.

3
Q

What is power?

A

Power is the rate at which work is done.

4
Q

What does the power rating of a car depend on?

A

The power rating of a car depends on its engine size, more powerful cars have greater fuel consumption.
- Some cars are more powerful than others. They travel faster and cover the same distance in a shorter time and require more fuel.

5
Q

What is an issue with high fuel consumption cars?

A

Fuel is expensive and cars with high fuel consumption are expensive to run.

6
Q

What is an issue with current fuels used today?

A
  • Fuels pollute the environment
    • Cars exhaust gases, especially carbon dioxide, are carbon dioxide are harmful
    • Carbon dioxide is also a major source of greenhouse gas, which contributes to climate change.
7
Q

What is the correlation between braking distance and speed?

A

Braking distance of a car increases with increasing speed, but not proportionally.

8
Q

What happens to kinetic energy when a car stops?

A

When a car stops its kinetic energy changes into heat in the brakes, tyres and road.

9
Q

What happens to the kinetic energy when the speed of a car doubles?

A

When the speed of a car doubles the kinetic energy and the braking distance quadruple.
- This is why there are speed limits, and penalties for drivers who exceed them.

10
Q

What is fuel consumption data based on?

A

Fuel consumption data is based on ideal road conditions for a car driven at a steady speed in urban and non urban conditions.

11
Q

What factors affect the fuel consumption of a car?

A

The factors that affect the fuel consumption of a car are:

  • The amount of energy required to increase it’s kinetic energy.
  • The amount of energy required for it to do work against friction
  • Its speed
  • How it is driven, such as excessive acceleration and deceleration, constant braking and speed changes.
  • road conditions, such as a rough surface.
12
Q

What are Electric cars?

A

Electric cars are cars that are battery driven or solar powered.

13
Q

What are the downsides to electric cars?

A
  • Battery takes up a lot of room
  • They have a limited range before recharging
  • They are expensive to buy, but the cost of recharging is low
  • Solar powered cars rely on the sun shining, and need backup batteries.
14
Q

What are problems associated with exhaust fumes?

A
  • Exhaust fumes from petrol fuelled and diesel fuelled cars cause serious pollution in towns and cities.
15
Q

How do battery driven cars indirectly contribute to global warming?

A
  • Battery driven cars themselves do not pollute the local environment, but their batteries need to be recharged, recharging uses electricity from a power station,.
    Power stations pollute the local atmosphere and cause acid rain.
16
Q

What is a positive of solar powered cars?

A

They do not produce any carbon dioxide emissions.

17
Q

What are issues with biofuels?

A

Biofuels may reduce carbon dioxide emissions, but this is not certain because deforestation leads to an increase in carbon dioxide levels.

18
Q

How are injuries reduced in a collision?

A

To reduce injuries in a collision, forces should be as small as possible.

19
Q

How can you reduce the force in a collision ( momentum ) ?

A

Spreading the momentum change over a longer time reduces the force.

20
Q

How can forces be reduced by reducing the acceleration?

A
  • Increasing the stopping or collision time.

- Increasing stopping or collision distance

21
Q

What are some safety features modern cars have to absorb energy when a vehicle stops suddenly?

A
  • Brakes that get hot
  • Crumple zones that change shape to absorb force
  • Seat belts that stretch
  • Air bags that inflate and squash
22
Q

What are some safety features that modern cars have to absorb energy on impact?

A
  • Crumple zones at the front and rear of the car absorb energy by changing shape or “crumpling”
  • Seat belts that stretch a little so that some of the person’s kinetic energy is converted to elastic energy.
  • Air bags absorb some of the person’s kinetic energy by squashing up around them.
23
Q

Why do some people not like wearing seatbelts?

A
  • There is a risk of chest injury.
  • They may be trapped in a fire
  • Drivers may be encouraged to drive less carefully because they know they have protection from a seat belt.
24
Q

What is an advantage of real tests over computer simulations?

A
  • Real tests provide more accurate data than computer simulations.
25
Q

What happens in ABS system?

A
  • Wheel speed sensors send information to a computer about the rotational speed of the wheels
  • The computer controls the pressure to the brakes, via a pump.
  • This is to prevent the wheels locking up
  • This increasing the braking force right before the wheels start to skid.
26
Q

What are some primary safety features of a car?

A
  • Cruise control which stops drivers becoming tired on a long journey and pressing harder on the accelerator.
  • Electric windows and paddle shift controls which allow the driver to concentrate on the road
  • ABS brake lock systems to prevent brakes locking up.

Decks in Phy: P1-P3 OCR Class (26):