Module 11

Question 1

1. Name the four fundamental forces in creation. Which two forces are really different aspects of the same force?

Answer 1

the gravitational force, the weak force, the strong force, and the electromagnetic force; the electromagnetic force and the weak force are really different facets of the same force

Question 2

2. Which is the weakest of the fundamental forces? Which is the strongest?

Answer 2

the weakest force is the gravitational force; the strongest one is the strong force

Question 3

3. Name the three principles of Newton’s Universal Law of Gravitation.

Answer 3

1- all objects with mass are attracted to one another by the gravitational force
2-the gravitational force between two masses is directly proportional to the mass of each object
3- the gravitational force between two masses is inversely proportional to the square of the distance between those two objects.

Question 4

4. The gravitational force between two objects (mass 1=10 kg, mass 2= 6kg) is measured when the objects are 10 centimeters apart. If the 10 kg mass is replaced with a 20 kg mass and the 6 kg mass is replaced with a 12 kg mass, how does the new gravitational force compare to the first one that was measured?

Answer 4

The new gravitational force, then, is 4 times larger than the old one.

Question 5

5. The gravitational force between two objects (mass1= 10 kg, mass2= 6 kg) is measured when the objects are 10 centimeters apart. If the distance between them is increased to 40 centimeters, how does the new gravotational attraction compare to the first one that was measured?

Answer 5

The new gravitational force, then, is 16 times smaller than the old one.

Question 6

6. The gravitational force between two objects (mass1= 1kg, mass2=2kg) is measured when the objects are 12 centimeters apart. If the 1 kg mass is replaced with a 5kg mass, the 2kg has is replaced with a 4 kg mass, and the distance between the objects is reduced to 4 centimeters, how does the new gravitational force compare to the first one that was measured?

Answer 6

The new gravitational force, then, is 90 times larger than the old one.

Question 7

7. If Venus orbits the sun because the sun exerts a gravitational force on it, what is the equal and opposite force required by Newton’s Third Law of Motion?

Answer 7

The equal and opposite force is the gravitational force that Venus exerts on the sun.

Question 8

8. What kind of force is necessary for circular motion? Give the definition of that force.

Answer 8

Centripetal force is required for circular motion.
Centripetal force: the force necessary to make an object move in a circle. It is directed perpendicular to the velocity of the object, which means it points toward the center of the circle.

Question 9

9. What are the three principles of circular motion?

Answer 9

1- circular motion requires centripetal force
2- the larger the centripetal force, the faster an object travels in a circle of a given size
3- at a given speed, the larger the centripetal force, the smaller the circle

Question 10

10. In an Olympic event called the ‘hammer throw,” an athlete twirls a massive ball on the end of a wire. Once he gets the ball twirling very quickly, the athlete releases the wire, allowing the ball to fly straight into the field. The person who throws the ball farthest this way is the winner:
    a. As the athlete twirls the ball faster and faster, will the wire have to apply more, less or the same amount of centripetal force?
    b. Suppose the athlete starts by gripping the wire close to the ball so the ball sweeps out a small circle. Then, keeping the speed of the ball constant, he allows some of the wire to slip through his hands so the ball sweeps out a larger and larger circle. Will the wire exert more, less or the same abut of force as the athlete makes his adjustment?

Answer 10

a. more force b. less force

Question 11

11. What is “centrifugal force”

Answer 11

it is a myth; there is no such force

Question 12

12. look in book on page 284 for this question (#12)

Answer 12

look in book

Question 13

13. List the inner planets and the outer planets.

Answer 13

inner- Mercury, Venus, earth and Mars

outer- Jupiter, Saturn, Uranus and Neptune

Question 14

14. List the planets of the solar system from the closest to the sun to the farthest from the sun.

Answer 14

Mercury, Venus, earth, Mars, Jupiter, Saturn, Uranus, Neptune

Question 15

15. List the planets that have rings.

Answer 15

Saturn, Uranus, Jupiter and Neptune

Question 16

16. Where are most of the asteroids in the solar system?

Answer 16

Most are the asteroids are between the orbits of Mars and Jupiter.

Question 17

17. What causes an asteroid to become a meteor?

Answer 17

perturbations in its orbit

Question 18

18. What are the three parts of a comet? Which of those parts is always present in a comet?

Answer 18

a nucleus, a coma and a tail; the nucleus is always present

Question 19

19. During what part of a comet’s orbit are all three parts present?

Answer 19

when the comet is close to the sun

Question 20

20. Are comets’ orbits circular or elliptical?

Answer 20

comet orbits are elliptical

Question 21

21. Where do most physicists think short-period comets come from?

Answer 21

Kuiper belt

Question 22

22. What causes gravity according to Einstein’s Theory of General Relativity?

Answer 22

gravity is caused by the fact that objects with mass bend space and time

Question 23

23. What causes gravity, according to the graviton theory?

Answer 23

gravity is caused by the exchange of particles called “gravitons”