Why if the resultant force is zero does a object thats moving keep moving in the same direction?

Question

I thought that even though the object is in motion, if there is no overall net force it cant move.
Any help?
Thanks

Answer 1

A resultant force causes acceleration.



Push an elephant on perfectly smooth ice and it slides, picking up speed.



Stop pushing (force =0) and the elephant doesn't suddenly stop - its inertia keeps it moving in a straight line until some other force acts.



Fire a bullet from a gun. The force (from compressed gas in the barrel) accelerates it along the barrel. You wouldn't expect the bullet to stop when it leaves the barrel just because there is no force. The bullet's inertia keeps it moving.

Answer 2

Yea, that is something that worried me a lot too but later on i understood.

See, the resultant force, if its is zero, then by newtons law (F = Ma)

F = 0 --> a = 0

acceleration is nothing but change in the velocity over time.

so, when a = 0, i.e' the change in velocity is zero. Not the velocity itself.

so, the velocity of the object before the forces getting balanced, if it is zero, then the object stays at rest

If the object was moving with some velocity prior to the forces becoming zero, it will continue with that velocity.

the most important thing you have to remember here is that acceleration is just the change of velocity, not the velocity itself.

Hope this helps. Have fun :)

Answer 3

force is responsible for the body to accelerate[in some case it does nothing like you are applying force on wall... :P :) nothing moves..see no motion]

similarly when an the resultant force is zero the object thats moving keep moving in the same direction with constant velocity.

if you are worried what its velocity would be....

it is equal to its velocity at the moment when the force becomes zero