State the type of energy transformation in the following cases: $(a)$ in a loudspeaker $(b)$ solar battery.

Calculate the power of an engine required to lift $10^{5} \text{ kg}$ of coal per hour from a mine $360 \text{ m}$ deep. [Take $g = 10 \text{ m s}^{-2}$]

Justify,giving proper reasoning,whether the work done in the following case is positive or negative: Work done by gravitational force when a bucket is pulled upwards.

An electric motor of power $100\, W$ is used to drive the stirrer in a water bath. If $50\%$ of the energy supplied to the motor is spent in stirring the water, calculate the work done on the water in one minute. (in $J$)

$A$ man of mass $60 \, kg$ runs up a flight of $30$ steps in $40 \, s$. If each step is $20 \, cm$ high,calculate the power of the man.

Seema tried to push a heavy rock of $100 \, kg$ for $200 \, s$ but could not move it. Find the work done by Seema at the end of $200 \, s$. (in $, J$)