Suppose a woman does of work and of heat transfer occurs into the environment in the process.

(a) What is the decrease in her internal energy, assuming no change in temperature or consumption of food? (That is, there is no other energy transfer.)

(b)

The internal energy is stored energy due to food intake. Treating the change in internal energy as the input energy and work done as output, what is her efficiency?

Efficiency: Eff:

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SumantLv10

6 Apr 2021

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What is the change in internal energy of a system which does 4.50 × 10⁵ J of work while 3.00 × 10⁶ J of heat transfer occurs into the system, and 8.00 × 10⁶ J of heat transfer occurs to the environment?

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A firebox is at 750 K, and the ambient temperature is
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(a) In air at 0°C, a 1.60-kg copper block at 0°C is set sliding at 2.50 m/s over a sheet of ice at 0°C. Friction brings the block to rest. Find the mass of the ice that melts.

(b) As the block slows down, identify its energy input Q, its change in internal energy , and the change in mechanical energy for the block–ice system.

(d) A 1.60-kg block of ice at 0°C is set sliding at 2.50 m/s over a sheet of copper at 0°C. Friction brings the block to rest. Find the mass of the ice that melts.

(e) Evaluate Q and for the block of ice as a system and for the block–ice system.

(f) Evaluate Q and for the metal sheet as a system.

(g) A thin, 1.60-kg slab of copper at 20°C is set sliding at 2.50 m/s over an identical stationary slab at the same temperature. Friction quickly stops the motion. Assuming no energy is transferred to the environment by heat, find the change in temperature of both objects.

(h) Evaluate Q and for the sliding slab and for the two-slab system.