Question #d67b8

1 Answer
Aug 19, 2017

Newton's first law of motion states that

An object acted on by no net force is in equilibrium, and either moves at a constant velocity or does not move at all.

In other words, objects in motion remain in motion, and objects at rest remain at rest unless acted on by an unbalanced force.

If an object's net force is zero (i.e. it is in equilibrium), it either moves at a constant velocity or has a constant position (i.e. it doesn't move). If an object has a constant velocity, by definition it has zero acceleration, because acceleration is a change in velocity.

A definition of force we can draw from this is a force is an interaction that changes the motion of an object from its previous motion.

Unless the force is counterbalanced by another force of equal magnitude in the opposite direction (so that the vector sum of the forces is zero), the object will change its motion and accelerate.