1. Universal Gravitation
Nathan Yoder
Makenna Cooper
Nicole Mcintosh

2. Major concepts
Gravity is the name that is given to the force of attraction between objects. Gravity is universal and is a very weak force compared to nuclear forces and electromagnetic forces. Gravity relies on mass and distance of objects for the size of force that is produced.

3. Historical perspective
Newton realized that the force that makes the moon orbit the earth and the force that makes an apple fall from a tree is the same force. He hypothesized that the moon was a projectile circling the earth under the influence of gravity. After trying to figure out the distance that the moon falls off of its straight line path and failling, Newton laid the groundwork for geometrical optics. After twenty years from his calculations on the moon's falling, Newton then revised his calculations with a corrected number and received agreement. He then published the law of universal gravitation.

4. Application of concepts
Universal gravitation is used when determining orbits of planets and also their paths while next to other planets. Gravity also is used in measuring weight of objects that are on a planet's surface. Gravity is also measured to figure out the escape speed of a rocket and the tangential speed for an object to go into orbit.

5. Think and explain
1. This simply means that the moon falls underneath the straight line path that it would normally take if no force acted on it. knowing this the moon doesn't get closer to the earth. It would however if its tangential velocity was reduced because it would move slower allowing earths gravity to attract it and pull it in.
2. The boulder is attracted to the earth more than the small stone hence its bigger weight. The both however, will have the same falling acceleration because the gravitational constant doesn't vary between the two objects.
3. All of the planets would move in a straight line path and thus flee away from our solar system.
4. No because the earth's mass would also have to double for the force to double.
5. a. The resulting number would be the gravitational constant.
b. This number would not differ from objects with different masses at different distances because it is a measurement for gravity.
6. The moon would fall 2.8 mm per second.
7. Your weight would be one fourth of what it normally is.
8. The weight of the person would decrease because the distance is increased the same as the mass, but since distance has a greater effect on the gravitational force you would weigh less.
9. This is consistant with the the law of gravity because every object with mass attracts to each other. This will mean that the universe will slowly stop expanding and then start to shrink.
10. Scientists don't doubt universal gravitation because everything observed does not contradict it so far. If something is found in the universe that contradicts universal gravitation it is possible for the theory to be debunked.

6. Review
1. Newton thought this because the moon does not follow a straight line path.
2. Newton discovered that they were the same force called gravity.
3. The moon falls around the earth. The moon also falls beneth the straight line that it would follow if no force acts on it.
4. Sideways velocity
5. Newton tested to see if the moon's fall beneath its straight line path that it should follow if no force acted on it was in correct proportion to the fall of any object on the earths surface.
6. The hypothesis needs to be backed up with tests before it can become a theory.
7. The planets don't crash into the sun because their tangential velocities are great enough to make them orbit the sun.
8. Newton discovered that gravity was universal.
9. It tells us that gravity is a very weak force.
10. The two masses are your own mass and the earth's mass. The distance is the distance from you to the center of the earth.
11. Gravity is reduced by the inverse square of the distance from the earth.
12. you would be 1/25 of your current weight if you were 5 times farther than the center of the earth, and would be 1/100 of your weight if you were 10 times farther than the center of the earth.
13. The earth is round because gravity pulled everything together, and no corners were able to form.
14. When two or more planets come close to eachother in orbit and their orbit is skewed from its origional path around the sun.
15. The Big Bang is scientific speculation that the universe came from a primordial fireball that exploded 15 to 20 billion years ago. The Big Crunch is an event that is speculated to occur in the future where the universe begins to collapse on itself due to gravity and become one unity.

7. Background information
Sir Isaac Newton was the first to fully recognize that the force holding any object to the earth is the same as the force holding the moon and the planets in their orbits. The force between any two bodies is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. The gravitational constant is represented by the symbol G and has the value, 6.670x10^-11N-m^2/kg^2.

8. Question
What is the force of gravity between the two people?

9. Conduction of experiment
Two people will stand side by side. I can use the formula: F=(G*M1*M2)/(R^2) to find the force of gravity between the two people.

10. Materials needed
-2 People
- Calculator
- Scale (in kilograms)

11. Procedure - Weigh both people
- Have both people stand 50 cm apart from each other
- Using the formula, calculate the force of gravity that exists between them

12. Safety precautions
None

13. Results F= (GM1M2)/R^2 F= ((6.67-10^-11)(97)(58))/(0.5)^2
F= 1.50x10^-6
I used the weight in kilograms of both people and plugged them into our formula to get the answer of 1.50x10^-6 N.

14. Analysis
We found that the force of gravity acting upon the two people was 1.50x10^-6 Newtons.

15. Conclusion supported by evidence
I came to the conclusion that with more weight amongst the two people, the more gravitational force will be acted upon them, to keep the lighter person from falling towards the heavier person. Without this force, the person with the weight of only 58 kg would fall towards the person with the weight of 97 kg.

16. Evaluation of hypothesis
I have found that my hypothesis was 1.50x10^-6 Newtons. Because my hypothesis wasn't a yes or no question, I can't say whether it was correct or incorrect, but I did the proper calculations to find the answer I needed.