1. PHYSICS

2. “I do not know of anyone who has gotten to the top without hard work.
Wednesday, 1/07/09 Physics
“I do not know of anyone who has gotten to the top without hard work.
That is the recipe.”
Margaret Thatcher

3. The Law of Universal Gravitation
Wednesday, 1/07/09 Physics
Every mass in the universe attracts every other mass:
The gravitational force of attraction between any two masses is proportional to each mass, but inversely proportional to the square of the distance between them.
center of mass to center of mass,
History of these concepts!!
NOTE: These are 3rd law forces!
“Weight” is the gravitational force between the Earth and objects on the Earth.

4. ex.
If two masses, m and M, are a distance R from each other, describe how the gravitational force between them changes in the following situations:
a) M is tripled
b) both m and M are doubled
c) the distance between them R is cut in half
d) m, M, and R are all doubled

5. What do we do to a proportion to make it into an equality?
We insert a constant!!
ex. Find gravitational force of attraction on a 55kg woman from a 95kg man who is 2.5m away.
ex. Find the gravitational force applied to 7.50kg object by the Earth if the object is on the surface of the Earth. (mass of the Earth = 5.98 x 1024kg, radius of the Earth = 6.38 x 106m)
If the only force acting on the object is the gravitational force, find the object’s acceleration.
N, BUT physics NOT chemistry, 9.8N, W = mg duh!!

6. Newton came up with the theory of universal gravitation.
(It united the concepts of falling objects on the earth
and the motion of planets around the sun.)
However, Henry Cavendish finally confirmed the law experimentally.

7. HW 31: WORKSHEET 1-6
Old book p. 139 – 140/ 1 - 6

8. HW 31
HW 31