Question

If the work put into a lever is 930 joules and the work accomplished is 870 joules, the efficiency of the lever is _____.

Answer 1

♥ C) 94%
♥ If the work put into a lever is 930 joules and the work accomplished is 870 joules, the efficiency of the lever is 94%.
♥ 870/930=93.5
♥ And rounded you get 94.

Answer 2

The correct answer to this question is C) 94%.

CALCULATION:

As per the question, the work put into a lever is 930 Joule.

Hence, input work W = 930 Joule.

Work accomplished by the lever is 870 Joule.

Hence, the output work W' = 870 Joule.

We are asked to calculate the efficiency of the level.

The efficiency of the lever is defined as the ratio of output work to the input work.

Mathematically efficiency $\eta=\ \frac{W'}{W}$

                                                $=\ \frac{870\ J}{930\ J}$

                                                 $=\ 0.935$

       In percentage, efficiency $=\ 0.935\times 100$

                                                 $=\ 93,5\%$

                                                 $=\ 94\%$                   [ans]

Hence, the efficiency of the lever is 94%.