physical science

When 90 kJ is removed from a 2-kg copper bar, its temperature drops from 200°C to 85°C. The specific heat of copper is

0.39 kJ/kg°C.

The specific heat of water is 4.2 kJ/kg°C. The heat needed to warm 8 kg of water from 20°C to 70°C is

1680 kJ.

The specific heat of water is 4.2 kJ/kg°C. How long will it take for a 2-kW heating element to raise the temperature of 30 kg of water from 20°C to 80°C?

63 min

Which of the following formulas relating temperatures on the Celsius and Fahrenheit scales is correct?

Tc = (5/9)(TF - 32°)

The freezing point of a substance is always lower than its

boiling point.

Radiation is emitted

by liquids, solids, and gases.

When a liquid freezes to become a solid,

it gives off heat.

When a liquid becomes a vapor,

it must absorb heat.

When heat is added to a body of matter, the resulting temperature increase does not depend upon

its shape.

A thermometer calibrated in the Celsius scale and a thermometer calibrated in the Fahrenheit scale are used to measure the same temperature. The numerical reading on the Fahrenheit thermometer

may be smaller or larger than that on the Celsius thermometer.

Heat transfer by convection occurs

only in liquids and gases.

A refrigerator

removes heat from a region and carries it elsewhere.

Of the substances below, the one with the highest specific heat is

water.

The specific heat of ice is 2.1 kJ/kg°C. When 50 kJ of heat is removed from 2 kg of ice initially at -5°C, the final temperature of the ice is

-17°C.

At which of the following Celsius temperatures will a Fahrenheit thermometer show the same reading in degrees?

-40°C