Concept explainers
(a)
The state of energy after it enters into the system where we pull a sled across a frozen lake. Also find whether the speed can remain constant or not if there is kinetic energy after doing the work.
(a)
Answer to Problem 1PQ
The thermal energy of ice and sled increases and the kinetic energy of sled also increases. Also constant speed can be maintained.
Explanation of Solution
Here the situation is pulling of a sled across a frozen lake. The system here is not completely frictionless. Therefore, the thermal energy of the system increases. The sled can move in constant speed. Also the kinetic energy of the sled can be increased as extra energy can be added to the system.
Conclusion:
Therefore, the thermal energy of ice and sled increases and the kinetic energy of sled also increase and constant speed can be maintained.
(b)
The state of energy after it enters into the system where we pull a sled up a snowy hill.
(b)
Answer to Problem 1PQ
Thermal energy will increase surely but the increase of kinetic energy is not sure.
Explanation of Solution
Here the sled is moved up a snowy hill. The system is not completely frictionless. So the frictional energy will increase. As the sled is moved up along a snowy hill against the gravity, the gravitational potential energy of the system will increase.
Conclusion:
Therefore, the thermal energy will increase surely but the increase of kinetic energy is not sure.
(c)
The state of energy after it enters into the system where a string wrapped around a pulley with a fixed axle is pulled.
(c)
Answer to Problem 1PQ
The thermal energy of the system increases, rotational energy may increase or remain constant.
Explanation of Solution
If the surface offers friction, the thermal energy of the system increases. If the spring rotates about the axle, the rotational energy increases. If the friction dissipates energy from the system, the rotational kinetic energy may increase or remain constant.
Conclusion:
Therefore, the thermal energy of the system increases, rotational energy may increase or remain constant.
(d)
The state of energy after it enters into the system where a cart with large wheels across a flat ground is pulled.
(d)
Answer to Problem 1PQ
The thermal energy of the system will increase, translational and rotational kinetic energy may also increase.
Explanation of Solution
If dissipative
Conclusion:
Therefore, the thermal energy of the system will increase, translational and rotational kinetic energy may also increase.
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Chapter 13 Solutions
Physics for Scientists and Engineers: Foundations and Connections
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