Molecular Physics | Thermodynamics Answers

During a brisk run, an adult human generates heat at a rate of about 1270 W. To remove this heat by evaporative cooling, what mass of water per second m/t must be evaporated from the body as sweat? The latent heat of vaporization of water at 37 °C (typical body temperature) is 24.2 × 105 J/kg.

The brass bar and the aluminum bar in the drawing are each attached to an immovable wall. At 21.9 °C the air gap between the rods is 1.55 x 10-3 m. At what temperature will the gap be closed?

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hen resting, a person has a metabolic rate of about 7.84 x 105 joules per hour. The person is submerged neck-deep into a tub containing 2.06 x 103 kg of water at 20.9 °C. If the heat from the person goes only into the water, find the water temperature in degrees Celsius after half an hour.

Complete the following statement: Most of the heat that is lost to space from the earth occurs by




convection.



both conduction and radiation.



radiation.



conduction.



both conduction and convection.

The filament of a light bulb has a temperature of 3.38 x 103 °C and radiates 60.0 W of power. The emissivity of the filament is 0.437. Find the surface area of the filament.

a person has a metabolic rate of about 7.84 x 105 joules per hour. The person is submerged neck-deep into a tub containing 2.06 x 103 kg of water at 20.9 °C. If the heat from the person goes only into the water, find the water temperature in degrees Celsius after half an hour.

The brass bar and the aluminum bar in the drawing are each attached to an immovable wall. At 27.1 °C the air gap between the rods is 1.67 x 10-3 m. At what temperature will the gap be closed?

A piece of lead [c = 128 J/(kg·C°)] is heated from 18.0 °C to 30.1 °C. The same amount of heat is added to a piece of copper [c = 387 J/(kg·C°)]. The mass and initial temperature of the copper are the same as for the lead. Determine the final temperature Tf of the copper.

The cavity within a copper [β = 51 × 10-6 (C°)-1] sphere has a volume of 1.190 × 10-3 m3. Into this cavity is placed 1.100 × 10-3 m3 of benzene [β = 1240 × 10-6 (C°)-1]. Both the copper and the benzene have the same temperature. By what amount ΔT should the temperature of the sphere and the benzene within it be increased, so that the liquid just begins to spill out?

When the temperature of a thin silver [α = 19 × 10-6 (C°)-1] rod is increased, the length of the rod increases by 3.1 × 10-3 cm. Another rod is identical in all respects, except that it is made from gold [α = 14 × 10-6 (C°)-1]. By how much ΔL does the length of the gold rod increase when its temperature increases by the same amount as that for the silver rod?