Question

A body of mass 5 kg initially at rest, is subjected to a force of 20N. What is the kinetic energy acquired by the body at the end of 10s.(Answer:4000J)​

Answer 1

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Given, mass of the body, m = 5kg;

Initial velocity of the body, u = 0;

Force acting on the body, F = 20N;

Time for which the force acts, t = 10s

If a is the acceleration produced in the body,

a = F/m

= 20/5

= 4m/s

Let v be the velocity of the body after 10 s.

Clearly, v = u + at

= 0+(4)×(10)

= 40m/s

Kinetic energy acquired by the body,

K.E. (Kinetic Energy) = 1/2mv^2

K.E. = 1/2 * 5 * (40)^2

K.E. = 1/2 * 5 * 1600

K.E. = 1/2 * 8000

K.E. = 4000

We also know that,

The unit we use for K.E. is Joule. It is represented by J.

So, The final answer is = 4000 J