Question

In a safety test, a car of mass 1000 kg is driven into a brick wall. Its bumper
behaves like a spring (k = 5 x 1000000 Nm-1) and is compressed by a distance of
3 cm as the car comes to rest. Determine the initial speed of the car.​

Answer 1

Answer:

Here the kinetic energy of the car is stored in the spring as potential energy of the spring.

1/2mu^2 =1/2kx^2

m × u^2 = 5*1000000*9*10^-4

1000 ×u^2 =45*100

u^2 = 4.5

So initial velocity of car is 2.12 m/s.