Given that,
Mass of the stone, m = 400 g = 0.4 kg
Initial speed, u = 20 m/s
It is climbed to a height of 12 m.
To find,
The work done by the resistance force.
Solution,
Let v is the final speed. It can be calculated by using the conservation of energy.

Work done is equal to the change in kinetic energy. It can be given as follows :

So, the required work done is 32.99 J.
A). m/s ... meters per second.
That's a speed.
b). m/s² ... (meters per second) per second.
Acceleration.
c). m²/s ... square meters per second.
Rate of change of area.
Meaningless unit, unless you happen to be
a painter of houses or a mower of lawns.
d). kg-m/s² ... (mass) x (an acceleration).
This is a unit of force.
In fact, it's the definition of "newton".
the puck recoils in each case.
larger mass stone gives puck greater recoil, smaller stone, smaller recoil
A) leaving a copper penny in vinegar until it turns green