# Physics Problems

Need help with these physics questions. Please provide explanations with answers.

1. On February 20, 1962, John Glenn became the first American to orbit Earth. If John Glenn weighed 640 N on Earth's surface, a) how much would he have weighed if his Mercury spacecraft had (hypothetically) remained at twice the distance from the center of Earth? b) Why is it said that an astronaut is never truly "weightless?"

2. Mr. Gewanter, whose mass is 60.0 kg, is doing a physics demonstration in the front of the classroom. a) How much gravitational force does he exert on 55.0-kg Martha in the front row, 1.50 m away? b) How does this compare to what he exerts on 65.0-kg Lester, 4.00 m away in the back row?

3. Astrologers claim that your personality traits are determined by the positions of the planets in relation to you at birth. Scientists argue that these gravitational effects are so small that they are totally insignificant. Compare the gravitational attraction between you and Mars to the gravitational attration between you and your 70.0-kg doctor at the moment of you birth, if the doctor stands 0.500 m away. NOTE:MM = 6.42 x 1023 kg, dE-M = 7.83 x 1010 m. This is the average distance between Earth and Mars. This distance varies as the two planets orbit the sun.

4. Our galaxy, the Milky Way, contains approximately 4.0 x 1011 stars with an average mass of 2.0 x 1030 kg each. How far away is the Milky Way from our nearest neighbor, the Andromeda Galaxy, if Andromeda contains roughly the same number of stars and attracts the Milky Way with a gravitational force of 2.4 x 1030 N?

5. Tides are created by the gravitational attraction of the sun and moon on Earth. Calculate the net force pulling on Earth during a) A new moon, b) a full moon, c) a first quarter moon. The diagram is intended to help your understanding of the situation but is not drawn to scale. (mM = 7.35x 1022 kg, mE= 5.98x 1024 kg, mS = 1.99 x 1030 kg, dE-M = 3.84 x 108 m, dE-S = 1.50 x 1011 m)

6. Two cars, one twice as heavy as the other, move down a hill at the same speed. Compared to the lighter car, the momentum of the heavier car is ________________.

7. On April 15, 1912, the luxury cruise liner Titanic sank after running into an iceberg. What was the cruise liner's speed when it collided with the ice berg if it had a mass of 4.23 x 108 kg ship and a momentum of 4.9 x 109 kg m/s?

8. Suppose you are traveling in a bus at highway speed on a nice summer day and the momentum of an unlucky bug is suddenly changed as it splatters onto the front window.

a) Compared to the force that acts on the bug, how much force acts on the bus. (more) (the same) (less)

b) Although the momentum of the bus is very large compared to the momentum of the bug, the change in momentum of the bus compared to the change in momentum of the bug is (more) (the same) (less)

c) Which experiences the greater acceleration ( HINT: Think of Newton's 2nd Law)? (bus) (both the same) (bug)

d) Which, therefore, suffers the greater damage? (bus) (both the same) (the bug of course!)

9. A 4.5-kg ham is thrown into a stationary 15-kg shopping cart. At what speed will the cart travel if the ham had an initial speed of 2.2 m/s?

10. Make two event chains showing what happens when a rolling ball (Ball 1) hits a resting ball (Ball 2) Use the phrases: gains momentum, hits Ball 2, is hits by Ball 1, loses momentum, rests, rolls, slows, down, stars rolling.

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