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Honors Physics
Chapter 5 – Motion in Two Dimensions Review Problems
1. A person is twirling a ball in a vertical circle with the center of rotation at his side, 2 meters above the
ground. If the length of the string holding the ball is 1meter and the time for one revolution is 0.67s and
the mass of the ball is 100 g…
What is the maximum force on the string? Where does it occur?
What is the minimum force on the string? Where does it occur?
What is the average force on the string? Where does is occur?
The person starts to increase the rate of rotation. If the string can withstand a force of 20 N, what is the
maximum velocity before the string will break?
When the string breaks (at the bottom of the rotation), what distance will the ball go before hitting the ground?
If the string does not break and the person slows down the rotation, what is the minimum velocity to remain in
rotation?
Honors Physics
Chapter 5 – Motion in Two Dimensions Review Problems
2. A 2 m tall person is twirling a 450 g mass horizontally just overhead. A 1 meter string has a breaking
strength of 100 N. How far will the mass land from the foot of the person, if the string should break?
(Assume the affect of the force of gravity on the mass is negligible.)
3. A satellite orbits the earth at a 3.84 x 10^8 m radius. The mass of this satellite is 7.38 x 10^22 kg.
Determine the period of its path around the earth. Can you identify this satellite?
4. A satellite is in a low circular orbit about the earth (i.e., it just skims the surface of the earth). What is
the speed of the satellite? How long does it take to make one revolution around the earth? ( The mean
radius of the earth is 6.38 x 10^ (6) m.)
Honors Physics
Chapter 5 – Motion in Two Dimensions Review Problems
Solutions:
1. Max force = 9.76 N, at the bottom, Min force = 7.8 N, at the top, Average force = 8.785 N, at the
sides, Max velocity = 13.79 m/s, horizontal distance ball will go = 6.23 m, Min velocity = 3.13 m/s
2. Velocity of mass when string breaks = 14.91 m/s, Time for mass to fall to ground = 0.639 s, Distance
of the mass from the foot of the person when the mass hits the ground = 9.53 m
3. Period of the satellite = 2.37 x 10^6 s = 27. 4 days, the satellite is the Moon.
4. The orbital velocity of the satellite = 7, 906. 959 m/s, The orbital period of the satellite = 5067.277 s
= 84.455 minutes = 1.408 hours