No force is necessary to
1. keep an object moving the way it is al-
ready moving.
2. cause a change in the motion of an ob-
ject.
3. stop an object from moving.
4. start an object moving.

1. keep an object moving the way it is already moving.

Explanation:

As we know that net force on the object is product of mass and its acceleration

so it is given as

here we know that

so when an object is applied by some force F then its motion is accelerated so here the velocity of the object will change

So if there is No force on the object then the velocity will remain same and hence there is no change in the motion of the object

so correct answer will be

1. keep an object moving the way it is already moving.

if the person is shown to have +90n, then ans is -10n.

if the person is shown to have -90n, then ans is +10n.

conduct current i mean it makes sense