Reducing Unwanted Energy Transfers

Question 1

What is the effect of frictional forces when something moves?

Answer 1

Frictional forces act against the movement, dissipating energy in the system.

For example, air resistance can transform kinetic energy to thermal energy.

Question 2

What is the role of lubricants in reducing friction?

Answer 2

Lubricants reduce friction between surfaces by providing a fluid layer that facilitates movement.

Lubricants are usually liquids like oil.

Question 3

What are two characteristics that can reduce the rate of energy transfer by heating in buildings?

Answer 3

• Thick walls
• Low thermal conductivity

Thicker walls and lower thermal conductivity result in slower cooling.

Question 4

What is cavity wall insulation?

Answer 4

Cavity wall insulation involves filling the air gap between two walls to reduce energy transfer by conduction and convection.

The air gap in cavity walls helps minimize heat loss.

Question 5

How does loft insulation help in energy retention?

Answer 5

Loft insulation reduces convection currents in loft spaces.

This helps keep heat from escaping through the roof.

Question 6

What is the function of double-glazed windows?

Answer 6

Double-glazed windows prevent energy transfer by conduction through an air gap between two sheets of glass.

This design is similar to cavity walls.

Question 7

True or False: Thick walls made from materials with high thermal conductivity are effective in preventing energy loss.

Answer 7

False

Low thermal conductivity is essential for effective insulation.

Question 8

Fill in the blank: _______ around doors and windows reduce energy transfers by convection.

Answer 8

Draught excluders

They help maintain indoor temperatures by blocking cold air.

Question 9

What happens to energy when there is air resistance acting on a falling object?

Answer 9

Energy is transformed from kinetic energy to thermal energy.

This is a result of frictional forces acting against the object’s motion.