Question

3.
Push a pebble lying on a surface. The pebble moves through a distance. You exerted a force on the pebble
and the pebble got displaced. In this situation work is done. A girl pulls a trolley and the trolley moves through
a distance. The girl has exerted a force on the trolley and it is displaced. Therefore, work is done. Lift a book
through a height. To do this you must apply a force. The book rises up. There is a force applied on the book
and the book has moved. Hence, work is done. A closer look at the above situations reveals that two conditions
need to be satisfied for work to be done: (i) a force should act on an object, and (ii) the object must be displaced.
(a) Can work done by external force on an object be negative?
[1]
(b) Write the SI unit of energy.
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(C) Write two conditions needs to be satisfied for work.
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(d) Define power.
[1]​

Answer 1

Answer:

b joule

d power is the amount of energy transferred or converted per unit time. In the International System of Units, the unit of power is the watt, equal to one joule per second. In older works, power is sometimes called activity. Power is a scalar quantity.