91影视

Very high in the Earth鈥檚 atmosphere, the temperature can be 700掳C. Yet an animal there would freeze to death rather than roast. Explain.

Why is wet sand at a beach cooler to walk on than dry sand?

If you hear that an object has 鈥渉igh heat content,鈥� does that mean that its temperature is high? Explain.

(II)The 1.20-kg head of a hammer has a speed of 7.5 m/s just before it strikes a nail (Fig. 14鈥�17) and is brought to rest. Estimate the temperature rise of a 14-g iron nail generated by eight such hammer blows done in quick succession. Assume the nail absorbs all the energy.

When you put an ice cube in a glass of warm tea, which of the following happens?

(a) Cold flows from the ice cube into the tea.

(b) Cold flows from the ice cube into the tea and heat flows from the tea into the ice cube.

(c) Heat flows from the tea into the ice cube.

(d) Neither heat nor cold flows. Only temperature flows between the ice and the tea.

(II)A 215-g sample of a substance is heated to 330掳C and then plunged into a 105-g aluminum calorimeter cup containing 185 g of water and a 17-g glass thermometer at 10.5掳C. The final temperature is 35.0掳C. What is the specific heat of the substance? (Assume no water boils away.)

A 22掳C day is warm, while a swimming pool at 22掳C feels cool. Why?

(II)A 0.095-kg aluminum sphere is dropped from the roof of a 55-m-high building. If 65% of the thermal energy produced when it hits the ground is absorbed by the sphere, what is its temperature increase?

Explain why air temperature readings are always taken with the thermometer in the shade.

(II)Estimate the Calorie content of 65 g of candy from the following measurements. A 15-g sample of the candy is placed in a small aluminum container of mass 0.325 kg filled with oxygen. This container is placed in 1.75 kg of water in an aluminum calorimeter cup of mass 0.624 kg at an initial temperature of 15.0掳C. The oxygen鈥揷andy mixture in the small container (a 鈥渂omb calorimeter鈥�) is ignited, and the final temperature of the whole system is 53.5掳C