A car's bumper is designed to withstand a 4.32 km/h (1.2 m/s) collision with an immovable object without damage to the body of the car. The bumper cushions the shock by absorbing the force over a distance. Calculate the magnitude of the average force (in N) on a bumper that collapses 0.150 m while bringing a 820 kg car to rest from an initial speed of 1.2 m/s. (Enter a number.)

3936 N

Explanation:

m = Mass of car = 820 kg

u = Initial velocity = 1.2 m/s

v = Final velocity = 0

d = Distance = 0.15 m

The work done is given by the change in the kinetic energy of the system

The magnitude of force is 3936 N

Explanation:

Given:

Now by the law of energy conservation, the work done is the energy compensated in bringing the car to rest.

where:

work done by the force F

change in kinetic energy

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