What is power?

An object thrown at a certain angle to the ground moves in a curved path and falls back to the ground. The initial and the final points of the path of the object lie on the same horizontal line. What is the work done by the force of gravity on the object?

$A$ lamp consumes $1000\, J$ of electrical energy in $10\, s$. What is its power (in $, W$)?

$A$ force of $7\, N$ acts on an object. The displacement is $8\, m$ in the direction of the force. What is the work done in this case (in $, J$)?

Soni says that the acceleration in an object could be zero even when several forces are acting on it. Do you agree with her? Why?

Look at the activities listed below. Reason out whether or not work is done in the light of your understanding of the term 'work'.
$1$. Suma is swimming in a pond.
$2$. $A$ donkey is carrying a load on its back.
$3$. $A$ windmill is lifting water from a well.
$4$. $A$ green plant is carrying out photosynthesis.
$5$. An engine is pulling a train.
$6$. Food grains are getting dried in the sun.
$7$. $A$ sailboat is moving due to wind energy.