A small stone of mass 0.5 kg is thrown vertically upwards from a point A with an initial speed of \(25 \mathrm {~m} \mathrm {~s} ^ { - 1 }\). The stone first comes to instantaneous rest at the point B which is 20 m vertically above the point A . As the stone moves it is subject to air resistance. The stone is modelled as a particle.
Find the energy lost due to air resistance by the stone, as it moves from A to B
The air resistance is modelled as a constant force of magnitude \(R\) newtons.
Find the value of R .
State how the model for air resistance could be refined to make it more realistic.