Physics Worksheet
Date _______________________ Period __ Name __________________________
PW newtons law gravitation questions 101105.doc
Newton’s Law of Universal Gravitation
Instructions: Answer the following on notebook paper. Show all work and make explanations complete.
1. Tell why Newton’s Law of Universal Gravitation is often referred to as an “inverse square law”. Refer to the
reference pages that accompany the End of Course test in physics. Locate one or more additional “inverse
square laws” and give a brief description.
2. What is the limitation of the extent of gravity according to Newton’s Law of Universal Gravitation?
3. Rearrange the equation to show why the units of G are in Nm2/kg2.
4. When Henry Cavendish set out to measure the value of G he reported that he was weighing the Earth. Why did
Cavendish’s work result in the weight of the Earth?
5. Using that vital statistics of the moon, and Newton’s equation, compute the mass of the moon and compare the
results of your calculations to the accepted value.
6. Use the Newton’s Law of Universal Gravitation calculator to do the following:
a. The edge of space is about 160. km up. How does the force of gravity change as you move toward the edge
of space?
b. About how far away from the surface of the Earth would you have to be to weigh about half of what you
weigh on the Earth's surface?
c. Compare the shapes of the graphs for distances from the Earth’s surface out to 100 km and for distances
from the Earth’s surface out to 10,000 km
d. What is the force of attraction that the Earth has for the Moon? What is the force of attraction that the
Moon has for the Earth?
e. How far away from the Earth must you be for the force of attraction to fall to exactly zero?
7. Compute the force of attraction experienced by two 225 N students at a distance of 50.0 cm.
8. Suppose an electron is 100. pm from the nucleus of an iron atom. Compare the force of gravitational attraction
with the force of electrostatic attraction. Note: To calculate the latter we must use Coulomb’s law, which is
one of the laws that you found in question 1 above.
Force (N)
9. Millard Missmore, a C- physics student at Podunk University, was to present this graph as part of a presentation
to his physics class, but he took a fall and bumped his head and now he is suffering from partial amnesia. Take
a look at the graph and determine what the graph is supposed to represent.
distance (km)