Question

A body of mass 5 kg starts at a velocity of 20 m/s and stops to rest after 5 seconds, what is the acceleration and retardation of the body and force applied against on it 3 points a) -4 m/s2 , 4m/s2 , 20 N b) 4m/s2 , -4m/s2 , -20 N c) 20 m/s2, -20 m/s2 , 100 N d) -20 m/s2, 20 m/s2, -100 N​

Answer 1

Explanation:

Correct option is

B

4000J

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

Answer 2

Explanation:

refer to the attachment

hope it's helpful to you