Forces
Marina Rushdyにより
1. Friction
1.1. opposite direction
1.2. slow down and stop
2. Air resistance
2.1. fricition force of air
2.2. opposite to the effect of gravity
3. pull
3.1. Move forward
4. Gravity
4.1. Mass
4.1.1. By increasing mass the gravity increase
4.2. Distance
4.2.1. By increasing distance the gravity decrease
4.3. solar system
5. Magnetisim
5.1. Magnet
5.1.1. different poles attract
5.1.2. like poles repel