MEDIUM
Lower Secondary Stage 7
IMPORTANT
Earn 100

If a pendulum swings in a vacuum it might swing forever. In air, the swings become gradually shorter. Suggest where some of the energy may have gone.  Remember, the conservation principle means that it cannot have been lost altogether.

Important Questions on Energy

MEDIUM
Lower Secondary Stage 7
IMPORTANT
Cambridge Lower Secondary Science Stage 7 : Student's Book>Chapter 8 - Energy>Exercise 8>Q 3
In an electric lamp, some energy is wasted. What does the conservation of energy tell us about the total of useful energy and wasted energy?
MEDIUM
Lower Secondary Stage 7
IMPORTANT
Cambridge Lower Secondary Science Stage 7 : Student's Book>Chapter 8 - Energy>Exercise 10>Q 1
A car burns fuel with an energy value of 85000 J. 68000 J of this is output from the engine as wasted heat energy and sound energy. Calculate how much useful energy is left for moving the car.
MEDIUM
Lower Secondary Stage 7
IMPORTANT
Cambridge Lower Secondary Science Stage 7 : Student's Book>Chapter 8 - Energy>Exercise 10>Q 3

For the fluorescent light bulb shown in figure, calculate the percentage of the input energy that is transferred usefully.

Question Image

MEDIUM
Lower Secondary Stage 7
IMPORTANT
Cambridge Lower Secondary Science Stage 7 : Student's Book>Chapter 8 - Energy>Exercise 10>Q 4

An old-fashioned filament lamp wastes 95% of the energy supplied to it. Draw an energy transfer (Sankey) diagram for it. 

MEDIUM
Lower Secondary Stage 7
IMPORTANT
Cambridge Lower Secondary Science Stage 7 : Student's Book>Chapter 8 - Energy>Exercise 10>Q 5
A car burns fuel with an energy value of 85000 J . 68000 J of this is output from the engine as wasted as heat energy. What percentage of the chemical fuel energy used by the car that will eventually end up as thermal energy?
EASY
Lower Secondary Stage 7
IMPORTANT
Cambridge Lower Secondary Science Stage 7 : Student's Book>Chapter 8 - Energy>Exercise 12>Q 1
Explain how you could use electricity from solar panels, together with other renewable energy sources, to get the electrical energy you need at any time.
MEDIUM
Lower Secondary Stage 7
IMPORTANT
Cambridge Lower Secondary Science Stage 7 : Student's Book>Chapter 8 - Energy>Exercise 12>Q 2
Name four sources of chemical energy that can be used in thermal power stations.
EASY
Lower Secondary Stage 7
IMPORTANT
Cambridge Lower Secondary Science Stage 7 : Student's Book>Chapter 8 - Energy>Exercise 12>Q 3

Choose from the following: (electrical energy heat kinetic energy potential energy)

 In the boiler, _____ is transferred to boil water and make fast-moving steam.