Thermal Physics

The SI unit for measuring heat is the

• Pascal

• Kelvin

• Joule

• Calorie

Which of the following statements about the kinetic theory of gases is NOT true:

• All molecules move with the same speed.

• Their average kinetic energy is directly proportional to the absolute temperature.

• All molecules make elastic collisions with each other and the walls of the container.

• The molecules travel in straight lines until they collide.

When one end of a cold metal spoon is placed upright in a cup of hot coffee, the other end gets hotter. Which one of the following best describes what is happening?

• Warmer molecules will rise to the top.

• The hot molecules produce thermal radiation that is then absorbed by the colder molecules.

• Higher-energy molecules hit lower-energy molecules, increasing their speed and therefore their temperature.

• Lower-energy molecules hit higher-energy molecules and the friction increases their temperature.

Tags

NGSS.HS-PS3-2

NGSS.HS-PS3-4

Three sealed flasks each containing 1 g of water, ice, and water vapour are at the same temperature. Which of the following is true about the internal energy of the substances?

• U water > U ice > U vapour

• U water = U ice = U vapour

• U water < U ice < U vapour

• U ice < U water < U vapour

A sealed container of air is kept at a constant temperature. What will happen to the speed of the molecules of air in the container as time passes?

• The molecules will all reach the same speed.

• Some molecules will speed up and others will slow down, but the average speed will be constant.

• The molecules will slow down.

• There will be no change.

A scientist is feeling sick and knows that if her temperature is a degree or more above 37.5°C she should go home from work. But all she has is a thermometer graduated in kelvin. What temperature does the thermometer need to be?

• 194.5 K

• 310.5 K

• 311.5 K

• 325.5 K

If two objects labelled B and C are both at thermal equilibrium with object A, which of the following must be true?

• Objects B and C are in thermal equilibrium with each other.

• Object B has a higher temperature than object C.

• Object C has a higher temperature than object B.

• Objects B and C are not in thermal equilibrium with each other.

Tags

NGSS.HS-PS3-4

A lead fishing sinker with a mass of 75.0 g and a temperature of 25°C is placed on a block of ice at 0°C, which then melts. If 75.0 g of water at the same temperature were poured on the ice, which of the following is true?

• The water would melt more ice than the lead fishing sinker.

• The water would melt less ice than the lead fishing sinker.

• The water would melt the same amount of ice as the lead fishing sinker.

• Neither the water nor lead fishing sinker would melt any ice.

Tags

NGSS.HS-PS3-4

The specific heat of a liquid is 1000 J kg-1 K-1. What amount of heat is needed to raise the temperature of 4.0 kg of liquid from 30°C to 40°C?

• 4.0 × 10³ J

• 2.0 × 10⁴ K

• 4.0 × 10⁴ J

• 4.0 × 10⁴ K

Tags

NGSS.HS-PS3-4

A cube of ice is placed in a foam cup and it begins to melt. The air temperature is 23°C. Which one of the following best describes the temperature of the water that is formed?

• less than 0°C

• 0°C

• room temperature

• greater than 0°C but less than room temperature

Tags

NGSS.HS-PS3-2

NGSS.HS-PS3-4