1. Universal Forces Chapter 12.4

2. Electromagnetic Forces Electric Forces Magnetic Forces They are the only forces that can both attract and repel.

3. Electric Forces Act between objects or particals that are charged Opposite charges attract. Like charges repel.

4. Magnetic Forces Opposite charges attract. Like charges repel.

5. Nuclear Forces There are two Nuclear forces: –Strong –Weak

6. Strong Nuclear Forces Is the force that hold the neutrons and protons in the nucleus. Distance: about the same as the diameter of a proton. 100 times stronger than the electric force of repulsion

7. Weak Nuclear Forces Acts over short distance Affects all particles, not just protons and neutrons Range is less than a strong nuclear force

8. Gravitational Force ATTRACTIVE force that acts between any two objects with mass Attractive = Mass =

9. Gravitational Force Attractive force is inversely proportional to the distance between the masses –As distance increases the gravitational force decreases Attractive force is directly proportional to the mass of the object –As the mass increases the gravitational force increases

10. Gravity is responsible for: The orbit of the moon around the Earth. Gravity provides the centripetal force needed to hold the moon around the Earth. The tides on the Earth are caused by the gravity of the moon pulling on the oceans. Satellites are held in orbit much like the moon is held in orbit.