Question

A body of mass 2 kg is sliding with a constant velocity of 4 m/sec on a frictionless horizontal table. The force required to keep the body moving with the same velocity is

• A. 8N
• B. 0N
• C. $2\times {10}^{4}N$
• D. $\frac{1}{2}N$

Answer 1

Answer: (B)

0N

When a body is sliding with a constant velocity on a frictionless surface, there is no force acting on the body in the direction of motion or against the direction of motion. It is a case of dynamic equilibrium. So, no force is required to keep the body moving with constant velocity i.e., constant momentum. If a frictional force acts on the body,an external force equal to the frictional force must be applied on the body in opposite direction to make the net force on it to be zero.