1. Universal Forces

2. Four Universal Forces:
Strong Nuclear Force Weak Nuclear Force Electromagnetic Force Gravitational Force

3. Strong Nuclear Force
Force inside nucleus that holds protons together. Like charges repel and this force overcomes that to hold it together

4. Weak Nuclear Force Force that is responsible for radioactive decay
Types of decay
-alpha: release of alpha particle (He nucleus)
-beta: release of electron
-gamma: release of light

5. Mass Energy Equivalence
E=mc2
Mass and energy can be converted into each other.
When mass decreases in a nuclear reaction (fission or fusion) energy is given off

6. Electromagnetic Force
Waves that transfer energy Responsible for light, communications, electricity and magnetism

7. Newton’s Law of Universal Gravitation
Physics

8. What is Gravity? Weakest of all forces Long range force
All objects in the universe are attracted to all other objects in the universe. The are affected by two factors: 1. mass
2. distance

9. Newton and Gravity
Besides the 3 laws of motion Newton came up with the Law of Gravitation between objects
Every particle in the universe exerts an attractive force on every other particle.
This law means that every object that has mass exerts a gravitational force on other objects that enter its gravitational field

10. If the cannonball were in orbit around the planet, what would it take to bring it back from orbit?

11. Newton’s Discovery
If objects are spread far apart the force of gravity will decrease.
If the objects are brought closer together the force of gravity will increase
Distance & Force are Inversely related
If the mass of one of the objects increases then the gravitational force will also increase.
Mass & Force are Directly Related

12. The Law of Universal Gravitation
G = 6.67 x Nm2/kg2 (universal gravitation constant )
FG = Force of Gravity between two objects (Newtons)
m = mass of the objects (kg)
d = distance between objects (m)

13. Inverse Square Law

14. What does this mean?
If the distance is doubled then the Gravitational force will decrease by 1/4th of what it was.
If the distance is halved then the Gravitational force will be 4 times as great.
A.K.A. Inverse Square Law

15. How Force is affected

17. Calculate the Force between you and the Earth using the following:
mearth = 6 x 1024 kg rearth = 6.4 x 106 m Calculate your mass in kilograms Solve for the Gravitational force between you and the earth. How does this value compare to your weight in Newtons?

18. Is there a Gravitational force between you and your neighbor?
Take measurements and find out using the Law of Gravitation.

19. Einstein and Gravity
In the early 20th century, Einstein took Newton’s concepts of gravity and proposed his theory of General Relativity. Einstein accurately described the deflection of light from massive objects. An eclipse in 1919 demonstrated what Einstein predicted- light is bent by gravity.