# Motion after force applied is removed

• Anjum S Khan
In summary, after the force is withdrawn at point B, the body will either continue moving with constant velocity or decelerate and come to rest depending on whether the surface is frictionless or has friction. On a frictionless surface, the body will maintain its inertia of rest/motion with uniform velocity, while on a frictional surface, the body will decelerate due to the frictional force acting opposite to motion. Both scenarios are in accordance with Newton's laws of motion.

## Homework Statement

Force is applied to a body from A to B, and then withdrawn.

Question: What happens after B ?
1. Will the body keeps accelerating after B ?
2. Will the body keeps moving with constant velocity after B ?

Consider both friction and frictionless surface.

2. The attempt at a solution

Case1 : Frictionless surface

1. No. The body stops accelerating because force is removed.
2. Yes.

Case2 : Frictional surface
1. No. The body stops accelerating because external force is removed.
2. No, body will deccelerate, and this decceleration would be found using frictional force which is now the only force acting on it.

Anjum S Khan said:
Force is applied to a body from A to B, and then withdrawn.

Question: What happens after B ?
1. Will the body keeps accelerating after B ?
2. Will the body keeps moving with constant velocity after B ?

Consider both friction and frictionless surface.

drvrm said:

Whether my answer/attempt is right or wrong ?

Anjum S Khan said:
Whether my answer/attempt is right or wrong ?

your answer has to be checked by Newton's laws of motion -
if no net force is acting on the body ,the body will maintain its inertia of rest/motion with uniform velocity.
so , on that basis your first set of answer is correct

now you have the iind part that the body is moving on a surface with frictional force acting-
so you have two forces and the net force will generate the motion - if the applied force is removed the body will not accelerate in forward direction but will be acted upon by the frictional force which acts opposite to motion so the body will decelerate and come to rest after some time.