Concept explainers
(a)
The change in kinetic energy of the disk.
(a)
Answer to Problem 35AP
Explanation of Solution
Given info: The radius of copper disk is
Write the equation for change in kinetic energy of the disk.
Here,
Write the equation of conservation of
Substitute
Write the formula for initial moment of inertia
Here,
m is the mass of the disk.
r is the radius of disk.
t is the thickness of copper disk.
The density of copper is
Substitute
Write the equation of conservation of angular momentum to calculate the final angular speed of the disk.
Further solve the above equation to calculate the final angular speed of the disk.
Here,
The value of coefficient of linear expansion
Substitute
Substitute
Conclusion:
Therefore, the change in kinetic energy of the disk is
(b)
The change in internal energy of the disk.
(b)
Answer to Problem 35AP
Explanation of Solution
Given info: The radius of copper disk is
Write the equation to calculate the change in internal energy of the disk.
Here,
Q is the energy required to change the temperature of substance.
c is the specific heat of the copper disk.
Specific heat of copper disk is
Substitute
Conclusion:
Therefore, the change in internal energy of the disk is
(c)
The amount of radiated energy.
(c)
Answer to Problem 35AP
Explanation of Solution
Given info: The radius of copper disk is
Write the equation for change in kinetic energy of the disk to calculate the amount of radiated energy.
Here,
Substitute
Conclusion:
Therefore, the amount of radiated energy is
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Chapter 19 Solutions
Physics for Scientists and Engineers
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