Thermal physics

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

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-PS3-2

NGSS.HS-PS3-4

A 2.0 kg solid has a specific latent heat of of fusion of 220 kJ kg^-1. An electric heater of power 1500 W is used to heat the solid. Assuming no heat loss, how long does it take to completely melt the solid at constant temperature?

• 290 seconds

• 290 minutes

• 150 seconds

• 150 minutes

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-2

NGSS.HS-PS3-4

A mass m of ice at a temperature of –5 °C is changed into water at a temperature of 50 °C.

Specific heat capacity of ice = c_i

Specific heat capacity of water = c_w

Specific latent heat of fusion of ice = L

Which expression gives the energy needed for this change to occur?

• 55 m c_w + m L

• 55 m c_i + 5 m L

• 5 m c_i + 50 m c_w + m L

• 5 m c_i + 50 m c_w + 5 m L

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-4

Energy is supplied at a constant rate to a fixed mass of a material. The material begins as a solid. The graph shows the variation of the temperature of the material with time.

The specific heat capacities of the solid, liquid and gaseous forms of the material are c_s c_l and c_g respectively. What can be deduced about the values of c_s c_l and c_g?

• c_s > c_g > c_l

• c_l > c_s > c_g

• c_l > c_g > c_s

• c_g > c_s > c_l

Which of the following is numerically equal to the specific heat capacity of the substance of a solid body?

• The thermal energy required to melt the body

• The thermal energy required to increase the temperature of unit mass of the body by 1K

• The thermal energy required to increase the temperature of the body by 1K

• The total kinetic and potential energy of all the molecules in the body

A fixed mass of an ideal gas in a closed container with a movable piston initially occupies a volume V. The position of the piston is changed, so that the mean kinetic energy of the particles in the gas is doubled and the pressure remains constant.

What is the new volume of the gas?

• $\frac{V}{4}$

• $\frac{V}{2}$

• $2V$

• $4V$

Tags

NGSS.HS-PS3-2

An ideal gas is contained in a thermally insulated cylinder by a freely moving piston.

The gas is compressed by the piston and as a result the temperature of the gas increases. What is the explanation for the temperature rise?

• The rate of collision between the molecules increases.

• Energy is transferred to the molecules by the moving piston.

• The molecules of the gas are pushed closer together.

• The rate of collision between the molecules and the walls of the cylinder increases.

Tags

NGSS.HS-PS2-1

NGSS.HS-PS3-4

A partially-inflated balloon is placed inside a bell jar. The bell jar is connected to an air pump. The air pump is switched on and air is removed from the bell jar.
What happens to the pressure and to the volume of the gas inside the balloon? 

• pressure decreases
  volume decreases 
• pressure decreases 
  volume increases 
• pressure increases 
  volume decreases 
• pressure increases 
  volume increases 

Boiling water is heated in a 2 kW electric kettle. The initial mass of water is 0.4 kg. Assume the specific latent heat of vaporization of water is 2 MJ kg^–1.

What is the time taken for all the water to vaporize?

• 250 s

• 400 s

• 2500 s

• 4000 s

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-4