Question

In a crash test, a test car of mass 1000 kg is moving at a speed of 37.9 m/s when it crashes into a wall. If the car comes to rest in 0.5 s, how much average power is expended in this process?

Answer 1

Here in this question, it is given that car crashes in 0.5sec that means the duration of the journey was 0.5 sec until body came to rest.

Given values

mass of car (m)= 1000kg

Speed of car(v)= 37.9 m/s

Time (t) = 0.5sec

Now, we have to find Avg Power expended in this process.

We know the general formula of Power is P=E/t....................(1)

Where E= Energy in our case the energy is kinetic energy because of motion.

The formula of Kinetic energy is E= 1/2m*v^2..................(2)

Substituting values in eq (2)

E=1/2*1000*(37.9)^2

E= 718205J

Now, putting the value of E in eq (1)

P= 718205/0.5

P= 1436410 W i.e. The avg power expended in this process.