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.

grav force prop 1/r squared 2r all squared is 4rsquared 1/4rsquared quartered

when two balls of the different masses are dropped from equal height, they reach the ground at the same time .this is because they experience the same acceleration.

the acceleration is independent of mass.

thus when they are dropped they will always maintain the same velocity and travel the same distance (neglect air resistance of course) at the same time.