Which of the following statements is correct?

$A$ shell is fired from a cannon with velocity $v \text{ m/s}$ at an angle $\theta$ with the horizontal direction. At the highest point in its path,it explodes into two pieces of equal mass. One of the pieces retraces its path to the cannon. The speed in $\text{m/s}$ of the other piece immediately after the explosion is:

$A$ $0.5\, kg$ ball is thrown up with an initial speed $14\, m/s$ and reaches a maximum height of $8.0\, m$. How much energy is dissipated by air drag acting on the ball during the ascent? (Take $g = 9.8\, m/s^2$)

$A$ water pump is driven by a petrol engine that pumps water from a depth of $30 \ m$ at a rate of $0.5 \ m^3/min$. If the efficiency of the pump is $70\%$, what is the power generated by the engine in $W$?

Two persons $A$ and $B$ are throwing a ball of mass $200 \ g$ at a wall as shown in the figure. The balls strike the wall perpendicularly at the same point at a height of $2 \ m$ from the ground. The balls strike the wall elastically at the same time and return back to $A$ and $B$ at the same time. They repeat this process. What is the average force exerted on the wall (in $N$)? (Take $g = 10 \ m/s^2$)

$A$ body of mass $2 \; kg$ initially at rest moves under the action of an applied horizontal force of $7 \; N$ on a table with coefficient of kinetic friction $= 0.1$. Compute the
$(a)$ work done by the applied force in $10 \; s$,
$(b)$ work done by friction in $10 \; s$,
$(c)$ work done by the net force on the body in $10 \; s$,
$(d)$ change in kinetic energy of the body in $10 \; s$,
and interpret your results.