$A$ 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.

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.

Explain that a flying bird possesses both potential and kinetic energy and provide their expressions.

An object of mass $10 \ kg$ is made to fall freely from a height of $10 \ m$. Complete the table:

Height of object $(m)$	$PE$ $(J)$	$KE$ $(J)$	Mechanical Energy $(J)$
$10$	...	...	...
$8$	...	...	...
$5$	...	...	...
Just above ground	...	...	...

Hence,state the law of conservation of energy.

$(a)$ The potential energy of a freely falling object decreases progressively. Does this violate the law of conservation of energy? Why?
$(b)$ An object is dropped from a height $h$. When is its
$(i)$ potential energy maximum?
$(ii)$ kinetic energy maximum?

$A$ body of mass $5\, kg$ initially at rest is subjected to a force of $20\, N$. Find the kinetic energy acquired by the body at the end of $10\, s$. (in $, J$)