91Ó°ÊÓ

A greased pig has a choice of three frictionless slides along which to slide to the ground.

Using the concept of the work done due to the weight of the pig moving to a height, we can get the work done by the body in the three cases of the frictionless slides.

Formulae:

The work done by an applied force,

$\mathbf{W}\mathbf{=}\stackrel{\mathbf{→}}{\mathbf{F}\mathbf{.}}\stackrel{\mathbf{→}}{\mathbf{d}}$ (1)

The force acting on a body due to its weight,

$\mathbf{F}\mathbf{=}\mathbf{mg}$ (2)

Gravitational force is the weight of the pig, and that is the same for all three cases considering the value of equation (2).

And height isthesame for all the slides, that is, say h metres .

So, work done for all the cases of slides is given using equations (2) in (1) as follows:

$\mathrm{W}=\mathrm{mgh}$

Hence, the rank of the slides according to the work done is the same for all three cases.