Question

The gravitational potential difference between the surface of a planet and a point `20 m` above it is `16 J//kg`. Calculate the work done in moving a `4 kg` body by `8m` on a slope of `60^@` from the horizontal.

Answer 1

Here `h=20m`
Gravitational potential difference `=16Jkg^(-1)`
The vertical distance through which the body has to be raised is `8sin60^@=8xx(sqrt(3)//2)=4sqrt(3)m`.
Since gravitational potential difference for a distance of `20 m` is `16J//kg`, hence the potential diference for a distance of `4sqrt(3)m` for a body of mass `4 kg` is `(16/20xx4sqrt(3))Jkg^(-1)`.
Work done in lifting a `4 kg` body through a vertical height of `4sqrt(3) m` is
`(16/20xx4sqrt(3))xx4=(64xx1.732)/5=22.16J`