Physics A.3 Energy, Work and Power

IB Physics

Energy

The ability to do work (rearrange your face)

Can be converted from one form to another

Kinetic Energy

The energy of motion

Kinetic energy = 1/2(m)(v)²

OR 1/2(p²/m)

Gravitational Potential Energy

Gravitational - the energy possessed by an object due to its position in a gravitational field.

Change in potential energy = (m)(g)(change in h)

Elastic Potential Energy

The energy stored in an elastic object due to its deformation

A spring that has been stretched a distance x has the potential energy 1/2(k)(x²)

Work

The energy transferred to or from an object by a force acting over some distance.

W = (F)(s)(costheta)

Theta is the angle between the force and displacement vectors

Power

The rate at which work is done

P = W/t

Conservation of Mechanical Energy

In an isolated system the total mechanical energy (kinetic+potential) remains constant. In a non-isolated system, the total mechanical energy plus the work done remains constant.