Car Design And Safety Flashcards
Brakes work against what?
Kinetic energy of the car.
What is done when you apply the brakes to slow down a car?
Work is done.
Breaks reduce what? by doing what?
Kinetic energy.
By transferring it into heat(and sound energy).
What cars make the use of energy?
New regenerative breaking systems used in electric or hybrid cars.
Regenerative brakes use the system that…
Drives the vehicle to do the majority of the breaking.
Rather then converting kinetic energy into heat energy what do regenerative brakes do?
Put vehicles motor in reverse.
Motor running backwards and wheels are slowed.
At the same time, the motor acts as an…
Electric generator, converting kinetic energy into electrical energy that is stored as chemical energy.
Where is the chemical energy stored?
Vehicles battery.
What is the advantage of regenerative brakes?
Store the energy of braking rather than wasting it.
Cars are designed to convert kinetic energy…
Safely in a crash.
If a car crashes it will ___ ____ very quickly.
Slow down.
When a car crashes what is converted?
A lot of kinetic energy is converted into other forms of energy in a short space of time.
In a crash, there’ll be a big…
Change in momentum over a very short time.
People inside feel huge forces.
Cars often do what to lessen the force on the passengers?
Increase the time over which momentum changes happen.
What are crumple zones?
Front and back of the car.
Crumple up on impact.
The car’s kinetic energy is converted into other forms of energy by what?
The car body as it changes shape.
What do crumple zones increase?
The impact time, decreasing the force produced by the change in momentum.
What are side impact bars ?
Strong metal tubes fitted into car door panels.
What do side impact bars do?
Direct kinetic energy of the crash away from passengers.
Where do side impact bars convert the kinetic energy to?
Other areas like crumple zones.
What are seatbelts?
Stretch slightly.
What do seat belts do?
Increase the time taken for wearer to stop.
Reduces forces in the chest.
Where is the kinetic energy absorbed?
By seat belt stretching.
What do air bags do?
Slow you down gradually.
Prevent you from hitting hard surfaces inside the car.
Cars have different…
Power ratings.
What determines how powerful a car is?
Size and design of cars engine.
The more powerful an engine is…
More energy it transfers from its fuel every second, so the faster it top speed can be.
What is the power output of a typical small car?
50 kW.
What is the power output of a sports car?
100 kW.
Cars also designed to be…
Aerodynamic.
What do cars being aerodynamic mean?
They are shaped in a way that air flows very easily and smoothly past them.
Minimising air resistance.
When do cars reach their top speed?
When resistive force equals the driving force provided by the engine.
Less air resistance to overcome…
Car reaches higher speeds before it happens.
Aerodynamic can have…
Higher top speeds.
