physics work and energy

work

• scaler

• work is done when force causes an object to move in the direction of force

• work is done in Joules

• W=Fd, Fdcos(), change in energy

energy (+ conservation of energy)

• scaler

• can be any type of energy (thermal, kinetic, potential)

• conservation of energy: energy cannot be created or destroyed, only transformed from one form to another

• energy is done in joules

scaler vs vector

• scaler: quantity described with magnitude

• vector: quantity described with magnitude and direction

power

• scaler

• how long it takes to do work or energy transfer over time

• P=w/t, or fv

• power is done in watts

GPE

• work done against gravity to lift an object at a certain heigh

• PE= mgh, PE= mg(hf-hg)

• often when it is above a reference line

• work will be positive when an object moves down and gravity moves down

elastic potential energy

• when there is energy stored in an object that is stretched or compressed and can return to its original state

if there is no external work done on a system:

the final energy will be the same as the initial because there is no change in energy

what does mechanical energy include

KE, PE, EPE

Wnet

1/2mv² (final) - 1/2mv² (initial)