AP Physics Unit 3 Terms - Work, Energy, and Power

Kinetic Energy (K)

Energy coming from movement. Scalar quantity measures in joules. (Ke=1/2mv²)

Work (W)

• Scalar Quantity; the amount of mechanical energy transferred in and out of a system (ΔE)

• Fdcos(θ)

System

• A single object or a collection of objects. Needs to be determined in order to find velocity, energy, momentum, etc.

• Anything outside is considered external

Conservative Forces

• Forces that are measured independent of the path

• Gravity/Springs

• Only depends on the initial and final configurations of the system

• Associated with potential Energy

Non-Conservative Forces

• Forces that are depended on the path of the system

• Takes away energy from a system

• Friction, Tension, etc

Potential Energy (U)

• Energy stored in an object at rest. Can be gravitational (U_g ) or elastic (U_s)

• Depends of the position of an object or system

Spring Potential Energy (U_s)

Potential energy of an idea spring, U_s= 1/2kx² (k=spring constant, x=displacement)

Gravitational Potential energy (U_g)

• Energy stored in an object due to it’s vertical position, U_g = mgh

Power (P)

• The rate at which work is done, W/t

• Fdcos(θ)/t ot Fv

• Measured in Watts

Walls (W)

The units that Power is measures in/the rate in which work is done

Joules (J)

The measurement for energy

Gravitational Field Strength

Gravitational Potential Energy on a larger scale, F_g = Gm₁m₂/r² (G = gravitational constant, m= mass, r = distance between objects)