Question

A body of mass 5kg at rest starts with an acceleration of 10m/s². What is the momentum of the body after 10s? What force is applied on the body?

Answer 1

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=

m

F

=

5

20

=4m/s

2

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,

E

k

=

2

1

mv

2

=

2

1

(5)×(40)

2

=4000j

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