Question

a body of mass 2 kg moving on a horizontalsurface with an initial velocity of 4 mps comes to rest after 2 secs if one wants to keep this body moving on the same surface with the velocity of 4 mps the force required is

Answer 1

Initial velocity (u) = 4 m/s

Final velocity (v) = 0 m/s

Let the acceleration provided by the friction be a.

Time taken to come to rest = 2 seconds

Using first equation of motion:

v = u + at

$a = \frac{v - u}{t}$

$a = \frac{0-4}{2}$

a = - 2 m/s^2

Hence, the force provided by the friction = mass × acceleration

= 2 × - 2

= - 4 N

Hence, we need 4 N force to keep the body moving at the same 4 m/s velocity.

F = 4 Newtons