The Nature of Forces

Forces can be exerted as a result of the following list, which does not include every possibility:

• Gravitational attraction between masses
• Elastic tension or compression
• Muscular tension
• Friction
• Electromagnetic effects
• Nuclear and other forces acting at the level of subatomic particles

The net force on an object is the sum of all the forces acting on it.

For forces acting in an x-y plane can act in either the x direction or the y direction, or can have comonents in both directions.

• Forces and/or force components in the x direction directly influence motion only in the x direction.
• Forces and/or force components in the y direction directly influence motion only in the y direction.

If the net force on an object is nonzero it will accelerate.

A stationary object has zero acceleration and so experiences zero net force.

An object with constant velocity has zero acceleration and so experiences zero net force.