Question

A body of mass 2 kg moving on horizontal surface with an initial velocity of 4 m/sec comes to rest after 2 sec. If one wants to keep this body moving on the same surface with a velocity of 4 m/sec, then the force required is

Answer 1

Answer:

Step-by-step explanation:

Mass (m) = 2kg (Given)

Initial velocity (u) = 4m/s (Given)

If there is no change in velocity then u = v , then mv - mv = 0, whereas when there is a change -

Using first equation of motion - a = v-u/t

= 0-4/2

= -4/2

= -2

Force required to keep the body in same velocity is F = m x a 

Change in velocity means acceleration - 

F = m x a 

F = 2 x 2

 F = 4 N 

Thus, according to Newton's first law of motion the body will continue to be straight motion or in a state of rest until an external force is applied on it , in this case a force of 4n is required to keep body moving with same velocity.

Hope it helps you....