Topic 2.1: Thermal Energy Transfers Questions

A liquid boils and becomes a gas.

Explain, using the particle model, why the gas has a much lower density than the liquid.

An oven is switched off with its door closed. Its temperature falls quickly at first and then more slowly.

Outline why the rate of cooling decreases.

Calculate the thermal energy needed to raise the temperature of 1.5 kg of copper from 18 degrees C to 68 degrees C.

The specific heat capacity of copper is 3.8 × 10² J kg⁻¹ K⁻¹.

A house cools down overnight after its heating is switched off. Its temperature–time graph becomes less steep.

Outline why.

The walls of a vacuum flask are separated by a gap with almost all the air removed.

Suggest why this reduces energy loss by conduction.

Calculate the energy supplied.

State what is meant by the specific heat capacity of a substance.

Explain why putting a lid on the cup improves an experiment that mixes hot and cold water.

A solid block is at room temperature.

What is its internal energy?

State the two contributions that together make up the internal energy of a substance.

State what is meant by the specific latent heat of vaporisation of a substance.

An ice cube at 0 °C is melting in a warm drink.

Which statement about the molecules of the ice is correct?

The insulation in a loft is replaced by a layer three times as thick, of the same material.

Explain the effect on the rate of energy loss through the loft for the same temperatures.

0.080 kg of steam at 100 °C is passed into a cold container, where it all condenses to water still at 100 °C.

The specific latent heat of vaporisation of water is 2.3 × 10⁶ J kg⁻¹.

Calculate the thermal energy released as the steam condenses.

Two blocks, P and Q, have the same mass.

They are each given the same amount of thermal energy.

Block P ends up hotter than block Q.

Identify which block has the larger specific heat capacity, and explain your choice.

A 50 W heater warms 0.20 kg of oil by 25 K in 3.0 minutes. No energy is lost.

What is the specific heat capacity of the oil?

Solid lead is melted.

Explain why molten lead has a lower density than solid lead.

State the one method of thermal energy transfer that can carry energy across a vacuum, and state what physically travels in that process.

A liquid metal has a density of 7.0 × 10³ kg m⁻³.

A sample of the liquid has a mass of 0.42 kg.

Determine the volume of the sample.

Molten iron solidifies at its melting point.

Which statement is correct?