Grade 9 Physics Review

An apple fell down from the apple tree to the ground. What type energy that has been converted?

• GPE to KE

• GPE to elastic energy

• KE to GPE

• elastic energy to KE

What types of energy that were dissipated when the falling apple hit the ground?

• sound and thermal

• kinetic and sound

• kinetic and thermal

• elastic and sound

What is energy stored in a slice of pizza?

• elastic energy

• chemical energy

• kinetic energy

• thermal energy

What is the useful energy in this diagram?

• electrical energy

• heat energy

• light energy

What is the percentage of energy efficiency in this diagram?

• 10%

• 90%

• 100%

Which energy source is one that is used to boil water to make steam in power stations?

• energy from tides

• energy from waves

• hydroelectric energy

• nuclear energy

Which energy source is renewable and reliably available at all times?

• coal

• geothermal

• nuclear

• wind

A certain machine is very efficient. What does this mean?

• It produces a large amount of power.

• It uses very little energy.

• It wastes very little energy.

• It works very quickly

Some processes are more efficient than others. Which expression gives the efficiency of a process?

• (total energy output/total energy) input × 100%

• (useful energy output/total energy input) × 100%

• (wasted energy output total energy input) × 100%

• (wasted energy output/useful energy output × 100%)

Three boxes each weigh 100 N. A man lifts all the boxes together from the ground on to a shelf that is 1.5 m above the ground. The man takes 2.0 s to do this. How much useful power does the man produce to lift the boxes?

• 75 W

• 225 W

• 300 W

• 900 W