P3 Flashcards
(38 cards)
How do speed cameras work?
- generally there are 2 speed cameras set up an equal distance apart
- this means that when you go past one it takes the picture of your car and then when you go past the other it takes a picture again
- they can then calculate how fast you were going throughout that particular distance
How do you calculate the speed of something on a Distance-Time Graph?
(distance - starting velocity (speed)) / final velocity
What is the meaning of acceleration and deceleration? What is it measured in?
- the change of speed of something
- a measure of how quickly something speeds up or slows down
- it’s measured in m/s(squared)
What is the equation for acceleration?
change in speed (m/s) / time taken for change (s)
What does an acceleration of -5m/s(squared) tell you about the motion of the object?
it shows that the object is decelerating at a rate of 5m/s(squared)
What does the area underneath the line in a Speed-Time Graph represent?
- the total distance travelled
What is the ‘thinking distance’?
the distance travelled by the vehicle from the point the driver realises he needs to brake to when he applies the brakes
What is the ‘braking distance’?
the distance it takes for the vehicle to stop once the driver applies the brakes
What is the ‘stopping distance’?
the thinking distance added to the braking distance
What does the ‘stopping distance’ depend on?
- the thinking distance
- the braking distance
What are the 3 main things that increase the thinking distance?
- the vehicle travelling faster
- if the driver is ill, tired or under the influence of alcohol or drugs
- if the driver is distracted or isn’t concentrating
What are the 4 main things that increase the ‘braking distance’? Why?
- the vehicle travelling faster: the greater the kinetic energy of the vehicle
- if there is poor weather/bad road conditions (e.g if its wet, slippery or icy: the friction between the tyres and the road is decreased, making it stop slower and travel faster)
- if the vehicle if in poor condition (e.g worn brakes: this means the braking force applied is not as strong means a smaller force on the brakes (less likely to stop), and tyres or under inflated tyres)
- the mass of the vehicle: increases its kinetic energy
How does the ‘thinking distance’ increase linearly?
double the speed = double the ‘thinking distance’
How does the ‘braking distance’ increase?
- by squaring it
double speed = quadruple the ‘braking distance’
triple speed = times the braking distance by 9
What does the amount of work done depend on?
- size of the force (in Newtons)
- distance the object has moved (in Metres)
What is power a measure of? What is it measured in?
- it is a measure of how quickly work is done
- it is measured in Watts
What is the definition for kinetic energy? What is it measured in?
- the energy an object has because of its movement
- Joules (J) or Kilojoules (KJ)
What is kinetic energy dependent on?
- speed (m/s)
- mass (kg)
What are 2 disadvantages of using fossil fuels?
- they are going to run out
- they pollute our environment
What are the alternate ways of powering cars? What are their advantages and disadvantages?
Electricity - advantages
- doesn’t emit pollution at the time of use
disadvantages -
- recharging the batteries uses electricity which is generated in power stations which DO cause pollution
Biofuels - advantages
- don’t emit pollution at the time of use
disadvantages -
- do produce pollution during production
What are the 3 frictional forces?
- friction
- drag
- air resistance
How ae frictional forces reduced?
- using a lubricant so that the object can slide through the air with less resistance
- changing the shape of the object (e.g stream lining it)
What can greater drag lead to?
energy loss and inefficiency and therefor greater fuel consumption
What are 5 safety features for protection during accidents in a car?
SAFETY FEATURES THAT ABSORB ENERGY OF THE CRASH:
- seatbelts
- air bags
- a crumple zone
- a collapsible steering column (this absorbs energy and breaks to avoid the driver being impales during an accident)
- a safety cage (this doesn’t absorb energy but it does keep the vehicle rigid to prevent it from collapsing in on the driver and possible passengers)
