1. Physics I
Gravity

2. 4 Known Forces: Gravity Electromagnetic
Strong Nuclear Force – holds protons and neutrons together in atomic nuclei; also holds quarks and gluons together in protons and neutrons
Weak Nuclear Force – results in beta decay (a type of radioactive decay) where an electron or positron is emitted

3. Newton – He’s the Man! Newton compared falling apple to “falling” moon
The apple and moon were both affected by Earth

4. Universal Law of Gravitation
“Everything pulls on everything else in a beautifully simple way that involves only mass and distance,” p.162.

5. Inverse Square Law
Masses are directly proportional to force of gravity
If you double the mass of one object you double the force of gravity
Distance between objects follows inverse square law
If you double the distance between objects you ¼ the force of gravity

6. Time for some calculations!