If mechanical work is done on an object,does its kinetic energy increase or decrease?

Derive the work-energy theorem for a variable force exerted on a body in one dimension.

$A$ body falls freely from a height $h$ in a gravitational field. Match the following:

Column-$I$	Column-$II$
$(1)$ Potential Energy $=$ Kinetic Energy	$(a)$ At height $\frac{2h}{3}$
$(2)$ Potential Energy $= 2 \times$ Kinetic Energy	$(b)$ Constant at every point
	$(c)$ At height $\frac{h}{2}$

$A$ force of $5\,N$,making an angle $\theta$ with the horizontal,acts on an object and displaces it by $0.4\,m$ along the horizontal direction. If the object gains a kinetic energy of $1\,J$,the horizontal component of the force is......$N$. (in $.5$)

$A$ block of mass $100 \, g$ moves on a rough surface. The heat produced when its velocity changes from $10 \, m/s$ to $5 \, m/s$ is ....... $J$.

$A$ bullet fired from a gun into a large wooden block loses half of its velocity after traveling $6 \ cm$ inside the block. How much further distance (in $cm$) will it travel before coming to rest?