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