IB Physics Unit 7

Gravitational Field

The force per unit mass experienced by a small point mass a distance r from a larger mass M, indicating how one object interacts with anything else.

Gravitational Potential Energy

Work done to bring a small point mass from infinity to a distance r; potential energy per unit mass caused by central mass M, represented by V sub g.

Equipotential Lines

Lines of equal gravitational potential encircling a mass, where objects can orbit with no work needed, with closer lines indicating higher energy levels.

Power

The rate at which work is performed or energy is transferred, calculated as P = W/T = FV, with efficiency indicating the percentage of useful power output.

Work-Energy Theorem

States that the change in mechanical energy of a system is equal to the work done on it, represented by Ei + W = Ef, where work can increase or decrease energy.

Zero Line

The reference point for gravitational potential energy calculations, where the position of the object's center of mass determines if PEg is positive, negative, or zero.

Work Equation

W = (F)(s)cos(θ), where work is positive when force and displacement are in the same direction, negative when in opposite directions, and zero when perpendicular.

Dot Product

A method of multiplying vectors to calculate work, where the component of one vector in the direction of the other is multiplied by the magnitude of the second vector and the cosine of the angle between them.