15.4 Pendulums

Gravity's restoring torque setting the period of simple, physical, and torsional swings via length, moment of inertia, and torsion constant.

University Physics Volume 1, 15.4 Pendulums

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6 exercises

15.4 Exercise 1

An engineer builds two simple pendulums. Both are suspended from small wires secured to the ceiling of a room. Each pendulum hovers 2 cm above the floor. Pendulum 1 has a bob with a mass of 10 kg. Pendulum 2 has a bob with a mass of 100 kg. Describe how the motion of the pendulums will differ if the bobs are both displaced by $12 °$ .

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15.4 Exercise 3

A pendulum clock works by measuring the period of a pendulum. In the springtime the clock runs with perfect time, but in the summer and winter the length of the pendulum changes. When most materials are heated, they expand. Does the clock run too fast or too slow in the summer? What about the winter?

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15.4 Exercise 6

Some people think a pendulum with a period of 1.00 s can be driven with “mental energy” or psycho kinetically, because its period is the same as an average heartbeat. True or not, what is the length of such a pendulum?

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15.4 Exercise 8

How long does it take a child on a swing to complete one swing if her center of gravity is 4.00 m below the pivot?

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15.4 Exercise 10

Two parakeets sit on a swing with their combined CMs 10.0 cm below the pivot. At what frequency do they swing?

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15.4 Exercise 12

A pendulum with a period of 2.00000 s in one location ( $g = 9.80 \text{m}/\text{s}^{2}$ ) is moved to a new location where the period is now 1.99796 s. What is the acceleration due to gravity at its new location?

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