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8 Energy – forces doing work

A family compares two vacuum cleaners, X and Y.

The Table shows information about the vacuum cleaners.

Table

Vacuum cleaner	Total power input in $W\text{W}$	Useful power output in $W\text{W}$
X	1600	480
Y	900	360

Calculate the efficiency of vacuum cleaner X.

[2]

Calculate the efficiency of vacuum cleaner Y and state which vacuum cleaner is more efficient.

[2]

Vacuum cleaner Y is used for 15 minutes.

Calculate the total energy supplied to vacuum cleaner Y.

[3]

A salesperson says:

'Vacuum cleaner X is better because it has a greater power input.'

Explain why vacuum cleaner X wastes more energy each second than vacuum cleaner Y.

[2]

8 Energy – forces doing work Questions