Physics Work and Energy

Work

The transfer of energy when a force moves an object in the direction of that force.

Formula for Work

W = Fd\cos(\theta)

Kinetic Energy (KE)

Energy of motion, calculated as KE = \frac{1}{2}mv^2.

Potential Energy (PE)

Stored energy due to position or configuration, such as PE_g = mgh.

Mechanical Energy (ME)

The total energy of motion and position; ME = KE + PE.

Conservation of Energy

Energy cannot be created or destroyed; it only changes from one form to another.

Power

The rate at which work is done; P = \frac{W}{t}.

Work-Energy Theorem

The work done on an object equals its change in kinetic energy; W = \Delta KE.

Displacement

The distance and direction an object moves from its starting point.

Force Angle (θ)

The angle between the applied force and the direction of motion.

When is no work done?

When there is no displacement or when the force is perpendicular to motion.

If force is perpendicular to motion

No work is done, because \cos(90°) = 0.

Potential Energy and Falling Objects

As an object falls, potential energy converts to kinetic energy.

Conservation of Mechanical Energy

If no friction or air resistance, total mechanical energy stays constant.

Increasing Kinetic Energy

Happens when an object speeds up.

Negative Work

Work done opposite to motion (like friction).

Power Units

Watts (W).

Work Units

Joules (J).

Kinetic Energy Units

Joules (J).

Potential Energy Units

Joules (J).