Vehicle safety Flashcards
How is the effect of a collison on a vehicle measured?
acceleration or deceleration of a vehicle
How can this be expressed in terms of gravity? suppose a vehicle hits a wall and its acceleration is -30ms-2
in terms of gravity its acceleration is -3g
impact force must have been 3x its weight
What happens as contact time increases in a collision?
the impact force reduces
What happens to two cards that collide and do not seperate?
they exert forces on each other until they are moving at the same velocity
the duration of the impact time is not the same as the contact time in this situation
How is impact time, acceleration and impact force worked out?
- t = 2s / (u + v)*
- a = (v - u) / t*
- f = ma*
What safety features do cards have to increase impact time
bumpers - give way in a low speed impact, increases time
crumple zone - engine compartment is designed to give way, if it was rigid the impact time would be very short
seat belts - prevent wearer from crasjomg into the frame, stopped more gradually
collapsible steering wheel - impact force lessened after steering wheel collapsing
airbags - reduces force, acts as cushion and increases contact time, more significantly the force of impact is spread over the contact area, which is greater than contact area with a seat belt
