State the energy conversions in a dry cell.

$(a)$ Define power. Give its $SI$ unit.
$(b)$ Taking the example of a simple pendulum, explain the variations in the forms of energy and the interconversions involved.

The work done on an object does not depend upon the

Justify,giving proper reasoning,whether the work done in the following case is positive or negative: Work done by an applied force on a body moving on a rough horizontal plane with uniform velocity.

$(a)$ How much work is done when a force of $1\, N$ moves a body through a distance of $1\, m$ in its direction?
$(b)$ Is it possible that a force is acting on a body but still the work done is zero? Explain giving one example.

$A$ body moves along a circular path. How much work is done in doing so? Explain.