Energy

Review & Continuation

Forms of Energy

• Potential– Chemical– Gravitational– Nuclear– Mechanical

• Kinetic– Motion– Sound– Thermal– Radiant– Electrical

Formulas

• F=ma• W=Fd <<or>> W=mad• P=W/t <<or>> P=mad/t• PE=mgh• KE=1/2mv2

An Example

Mass= 10 kg

Height= 1 m

Gravity=9.8m/s/s

PE=mghPE=(10)(9.8)(1)PE=98 Joules

An Example

Mass= 10 kg

Height= 0.5m

Gravity=9.8m/s/s

PE=mghPE=(10)(9.8)(0.5)

PE=49 Joules

Conservation of Energy

• 1st Law of Thermodynamics– Energy cannot be created or destroyed

• If the distance changed from 1m to 0.5m, the amount of PE decreased from 98 to 49

• Where did the energy go?– It was converted from PE to KE!