P3c Flashcards
1
Q
How is thinking distance affected?
A
- how fast you are going, the faster you are going the further you’ll go
- how dopey you are, affected by : tiredness, drugs, alcohol, disturbances, lack of concentration
2
Q
How is stopping distance affected?
A
- the faster you are going the further it takes to stop
- the heavier the vehicle the longer it takes to stop
- quality of brakes
- quality of grip
3
Q
What do brakes depend on?
A
- how much force applied
- brakes must be checked and maintained regularly
- faulty and worn brakes means you can’t brake with as much force
4
Q
What does grip depend on?
A
- friction
- weather conditions, wet and icy roads are more slippery than dry roads
- road surface
- tyres, a tyre without tread (i.e bald tyres) will ride on layers of water on roads and skid very easily (this is called aquaplaning)
5
Q
How can drivers avoid accidents?
A
- leave enough space between their car and the car in front of them
- enough space means the stopping distance for what they are driving at
- follow speed limits
6
Q
How does speed affect braking distance?
A
- braking distance has a squared relationship with speed
- when speed is doubled braking distance increases 4-fold
- when speed trebles braking distance increases 9-fold
- has a quadratic graph
7
Q
How is momentum determined?
A
-the greater the mass of an object and the greater velocity the more momentum an object has
8
Q
How are changes in momentum caused?
A
- a change in velocity
- any force added to an object overtime causes changes in velocity
9
Q
What do changes in momentum cause?
A
- the time taken for a change in velocity determine how big or small a force will be
- short time means high force
- long time means low force
10
Q
Name and describe some car safety features.
A
- crumple zones, crumple and change on impact increasing time take for car to stop
- seat belts, stretch slightly, increasing time taken for wearer to stop, reducing force acted on the chest
- air bags, also slow you down more gradually
11
Q
What are car safety features desired to do?
A
- to lower force by slowing down and object over a longer time
- reducing injuries as some are caused by rapid deceleration
- increase collision time to reduce deceleration
- reduce force and deceleration
- safety features change shape during crashes, which helps absorbs some kinetic energy inside the car
12
Q
How do ABS brakes help driver take control in emergencies?
A
- anti-lock braking system
- helps drivers keep control of the car’s steering when braking hard
- ordinary brakes would lock the wheels so they can’t turn, causing the car to skid
- ABS locks automatically pump on and off to stop wheels locking and preventing skidding
- also giving the car shorter braking distance which could prevent a collision with a car in front
13
Q
How do safety features save lives?
A
- safety features are rigorously tested to see how effectively they save lives or stop injuries in an accident
- crash tests have show that wearing a seat belt reduces the number of fatalities by 50%
14
Q
How does speed affect thinking distance?
A
- thinking distance increases at the same rate as speed
- directly proportional to speed
- linear graph
15
Q
How are roads made safer?
A
- placing structures like crash barriers and escape lanes in dangerous locations (sharp bend, steep hill)
- these structures are designed to increase the time and distance of any collision (reducing collision force)
16
Q
How are road safety features tested?
A
- crash testing
- crashing cars containing cars, with and without the safety feature, and watching slow motion footage to see results
- dummies have sensors at different places on their body to show where a real person would be injured and how bad the injury would be
- repeated using different cars at different speeds and different sized dummies
