Question

An object with a mass of `4 kg` is hanging from an axle with a radius of `8 cm`. If the wheel attached to the axle has a radius of `24 cm`, how much work would it take to turn the wheel `2 cm`?

Answer 1

As shown in the figure
The radius of the Wheel `R=24cm`
The radius of the Axle `r=8cm`
The mass of the object `m=4kg`
The Weightof the object `W=mg=4xx9.8N`
P is the applied force.
The Displacement of Applied force(P) `=d=2cm=0.02m`
The working principle of wheel -axle system may be compared with the working principle of First Kind of lever

So
`PxxR=Wxxr=>P=Wxxr/R=4xx9.8xx8/24N`

Hence the Work done `=Pxxd=4xx9.8xx8/24xx0.02J=0.26J`