# If an object is moving then a net force must be acting on it

This is part of a series on common misconceptions.

Is this true or false?

If an object is moving, then a net force must be acting on it.

**Why some people say it's true:** To move an object, we have to push it by applying a force.

**Why some people say it's false:** Because there is no force acting on light but still it moves.

The statement is $\color{#D61F06}{\textbf{false}}$.

Explanation:

Any particle that is moving with constant speed will have a net force of zero acting on it. When we push any object, we are applying a force to accelerate it. By Newton's second law, acceleration is produced when a force acts on a mass. So it is not necessary that "if an object is moving then a net force must be acting on it." There are many examples moving with constant velocity (i.e. $F_{net}=0$), such as

- Light moves with constant speed.
- Your laptop is also moving with constant speed (i.e. $0$ m/s).
- Bullet fired from a gun moves with constant speed.

**See Also**

**Cite as:**If an object is moving then a net force must be acting on it.

*Brilliant.org*. Retrieved from https://brilliant.org/wiki/if-an-object-is-moving-then-a-net-force-must-be/