"With our day to day experience, we must expert some force on an object to keep it moving".
Which acts on the body? Either force or net forces?

"With our day to day experience, we must expert some force on an object to keep it moving". By which law, you can support the above lines?

In which of the following cases the net force is not zero ?

Lift an object up from the ground. Work done by the force exerted by you on the object moves it in upward direction. Thus the force applied iis in the direction of displacement. However there exists a force gravitational in the object at the same time * Which one of these forces is doing positive work ? * Which one is doing negative work ? * Give reasons.

If an external force and the frictional force acting on a body cancel each other and keep the body at rest, the frictional force is

In Which of the following cases the net force acting on the body is not zero ?

No work is done by a force on an object if a) the force is always perpendicular to its velocity b) the force is always perpendicular to its acceleration .c) the object is stationary but the point of application of the force moves on the object d) the object moves in such a way that the point of application of the force remains fixed.