Physics 0088 Spring 2023 Homework #3
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Homework #3
Physics 0088
Spring 2023
Due: 5PM on Thursday, February 16, 2023
The first 12 problems are worth 6 points each. See below for the point values of the final questions.
1. Consider the Moon’s orbit around the Earth. In what direction is the Moon’s acceleration due to the gravitational attraction between the Moon and Earth?
A. Parallel the direction of the Moon’s motion.
B. Opposite the direction of the Moon’s motion..
C. Perpendicular to the instantaneous direction of the Moon’s motion..
D. Toward the center of the Earth.
E. Both A & D
F. Both C & D
2. Ifthe Earth were to somehow instantly collapse to 1/10 of its present radius without its mass chang- ing, by how much would your weight change?
A. Increase by a factor of 10.
B. Increase by a factor of 100.
C. Stay the same.
D. Decrease by a factor or 10.
E. Decrease by a factor of 100.
3. If the Earth were to somehow expand to 10 times its present radius without its mass changing, how would your weight change?
A. Increase by a factor of 10.
B. Increase by a factor of 100.
C. Stay the same.
D. Decrease by a factor or 10.
E. Decrease by a factor of 100.
4. The acceleration due to gravity on Jupiter’s Moon Callisto, is about 1/10 of that on the surface of the Earth. If your mass on Earth is 50kg, what is your mass on Callisto?
A. 50 N
B. 50 lbs.
C. 5 kg.
D. 50 kg.
E. 5 N.
5. The order of magnitude of the gravitational constant G is 10- 11 N m2/kg2 in SI units. Using this fact, what is the order of magnitude of the gravitational force between you and one of your fellow students in class?
A. 10- 11 N
B. 10-9 to 10-7 N
C. 10-2 to 1 N
D. 1011 N
E. 107 to 109 N
6. The mass of Jupiter is 1027 kg. It orbits at a distance from the Sun of about 5 AU, which is about 1012 m in SI units. Approximately, what is the ratio of the gravitational force that Jupiter exerts on your body to the gravitational force that a fellow student in your class exerts on your body?
A. Jupiter exerts a force that is larger by 1027 .
B. Jupiter exerts a force that is larger by a factor of 1012 .
C. Jupiter exerts a force that is between roughly 1 and 10 times as large.
D. Jupiter exerts a force that is smaller by 1027 .
E. Jupiter exerts a force that is smaller by a factor of 1012 .
7. Suppose you jump to highpoint a football and are 1m above the surface of the Earth. The mass of the Earth is approximately 1025 kg. At the instant that you are 1m above the surface of the Earth, approx- imately what is your acceleration toward the Earth’s surface?
A. 1 m/s
B. 10 m/s
C. 81 m/s2
D. 10 m/s2
E. 1025 m/s2
8. Suppose you jump to highpoint a football and are 1m above the surface of the Earth. The mass of the Earth is approximately 1025 kg. At the instant that you are 1m above the surface of the Earth, approx- imately what is the acceleration of the Earth toward your body?
A. 10 m/s
B. 10 m/s2
C. 1025 m/s2
D. 10-22 m/s2
E. 1022 m/s2
9. Suppose you have access to an elevator that is attached to a small engine. The engine only has a finite amount of fuel. This fuel can provide only 4000 J of energy. Suppose that you have a mass of 80 kg, which corresponds to a weight of 800 N (or about 176 lbs). How high can this engine lift you without running out of energy?
A. 800 m
B. 4000 m
C. 5 m
D. 10 m
E. 50 m
10. In class, I did an experiment in which I dropped a weight attached by a string to an electric genera- tor. When I did this the generator produced electricity, which was able to provide energy to a small light bulb. In this process, energy was converted from one form to another. Which combination best describes this transformation.
A. The kinetic energy of the weight was converted, in part, to electrical energy.
B. The chemical potential energy of the weight was converted into electrical energy.
C. The kinetic energy of the weight was converted, in part, into the chemical potential energy of the weight.
D. The kinetic energy of the weight was converted into the potential energy of the weight, causing the light to turn on.
E. The gravitational potential energy of the weight was converted, in part, into electrical ener- gy which caused the light to turn on.
11. In a crash test, a 1000 kg automobile moving at 67 mph (30 m/s) moves toward a steel-reinforced brick wall. Prior to hitting the wall, how much kinetic energy did the automobile have?
A. 1000 J
B. 30 J
C. 300,000 J
D. 30,000 J
E. 450,000 J
12. In the previous crash test, the car comes to a stop after making an impact with the wall. Discuss what happens to the kinetic energy of the car? Energy must be conserved, but where does it go?
13. Consider a Boeing 747 Aircraft. It has a mass of about 105 kg (that’s about 200 tons). A typical long- haul aircraft cruises at an altitude of approximately 40,000 ft, which is roughly 12,000 m in SI units. A 747 can cruise at roughly 550 mi/hr, which is about 250 m/s. What is the kinetic energy of a cruis- ing, fully-loaded 747 Aircraft? [Worth 8 points]
14. Consider a Boeing 747 Aircraft. It has a mass of about 105 kg. A typical long-haul aircraft cruises at an altitude of approximately 40,000ft, which is roughly 12,000m in SI units. A 747 can cruise at roughly 550 mi/hr, which is about 250 m/s. What is the potential energy of a cruising, fully-loaded 747 Aircraft? [Worth 10 points]
15. Consider a Boeing 747 Aircraft. It has a mass of about 105 kg. A typical long-haul aircraft cruises at an altitude of approximately 40,000ft, which is roughly 12,000m in SI units. A 747 can cruise at roughly 550 mi/hr, which is about 250 m/s. In order to cruise, a 747 must typically exert a force of 200,000N or so with its engines. For what distance journey is the work done by the engine while cruising approximately equal to the potential energy of the aircraft at a cruising altitude of 12,000m? [Worth 10 points]
2023-02-15