Energy(chapter 5)• Energy – the ability to do work

• Electrical, thermal, chemical, etc.

Kinetic energy – energy of motion

• KE = ½ mass x velocity2

• The label is the kg m2/s2…or the Joule (J)• How does friction affect KE?

Gravitational Potential Energy• Energy stored by objects due to their position above Earth’s

surface• GPE = mgh g = 9.8m/s2

• Let’s look at the connection between GPE and KE…

Potential energy• Stored energy or energy of position• Elastic PE – energy that can be stored in something that

can be stretched or compressed

• Chemical PE – energy stored in chemical bonds

Law of Conservation of Energy

• Energy is neither created nor destroyed, but transformed!• Light bulb (electrical light)• Mechanical energy = PE + KE

Nuclear reactions• Fusion – the combining of 2 hydrogen nuclei

• Fission – splitting one atom into 2!