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

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

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

What is the correct definition of:

Temperature ?

• A measure of the internal energy of a body

• The sum of all the kinetic and potential energies of the molecules within a substance

• A measure of the kinetic energy of the particles in a substance

What is the correct definition of:

internal energy ?

• A measure of the internal energy of a body

• The sum of all the kinetic and potential energies of the molecules within a substance

• A measure of the kinetic energy of the particles in a substance

What is the correct definition of:

Boyle's law ?

• The volume of a fixed mass of an ideal gas at constant temperature is inversely proportional to its pressure

• The volume of an ideal gas at constant pressure is directly proportional to its absolute temperature

• The pressure of a fixed mass of an ideal gas at a constant volume is directly proportional to its absolute temperature

What is the correct definition of:

ideal gas ?

• A gas whose particles have negligible volume, have negligible forces between them and undergo elastic collsions. An ideal gas will perfectly obey Boyle's law

• A gas whose particles have negligible volume, have negligible forces between them and undergo elastic collisions. An ideal gas will perfectly obey Charles' law.

• A gas whose particles have fixed volume, have negligible forces between them and undergo inelastic collisions. An ideal gas will perfectly obey Boyle's law

A sample of water has a mass of 3.40 kg and a specific heat capacity of 4200 J/kg.K. How much energy will it require to raise its temperature from 300 K to 380 K?

• 2.34 MJ

• 1.14 MJ

• 1.45 MJ

A material has a mass of 34.0 g and a specific latent heat of fusion of 3.40 x 10^3 J/kg. How much energy will the material need to lose to turn it from a liquid into a solid?

• 1156 J

• 116 J

• 116 kJ