The unit for force in the metric system is the newton or kilogram meter per second squared, while the unit for force in the U.S. standard system is the pound force. The formula for force is mass times acceleration.
Force is the push or pull on an object with mass, causing the object to accelerate in a certain direction. Force is known as a vector quantity, as it possesses both magnitude and direction.
There are two main categories of force: contact force and action-at-distance force. Examples of contact forces include friction, tension, normal and applied force. Gravitational, electrical and magnetic force are examples of action-at-distance force. Sir Isaac Newton created the three laws of motion to define force.