Work, Energy, Power, Momentum, and Impulse Concepts

Work

Work is done when a force causes a displacement of an object.

SI unit of work

Joule (J)

Kinetic energy

Kinetic energy is the energy of an object in motion.

Potential energy

Potential energy is the energy stored due to an object's position, typically gravitational.

How does kinetic energy change when speed is doubled

The kinetic energy quadruples.

Work-energy theorem

The work done on an object is equal to the change in its kinetic energy.

Power

Power is the rate at which work is done or energy is transferred.

Unit of power

Watt (W)

Relationship between work, power, and time

P=Wt

What happens to power if the time to do work is halved

Power doubles.

Momentum

the quantity of motion of a moving body, measured as a product of its mass and velocity

Impulse

Impulse is the change in momentum, J=Δp, and is equal to force multiplied by time.

Momentum in a regular collision

Momentum is conserved in a collision, unless external forces act on the system.

Calculation of impulse

Impulse is equal to the change in momentum: J=Δp=F×t.

Effect on momentum with longer force application

The impulse (and therefore the change in momentum) increases.