Question

Question #ca57c

Answer 1

Since Gravitational field is a Conservative field, potential energy does not dependent on curved path followed by the crate.

Let `h` be the vertical height lost by the crate of mass `m` while moving from Point `A` to `B`.

Lost of Potential energy `Delta PE=mgh`
Given `mg=300N`, and acceleration due to gravity is `9.81ms^-2`

Change in kinetic energy`DeltaKE="Final kinetic Energy"-"Initial Kinetic Energy"`
`DeltaKE=1/2m(8)^2-1/2m(1.2)^2`
`=>DeltaKE=32m-0.72m`
`=>DeltaKE=31.28m=31.28xx300/9.81=956.57J`

By Law of Conservation of Energy, this loss gets partly converted into change in kinetic energy and partly is lost as work done against friction `W_f`. Therefore we have
`DeltaPE=DeltaKE+W_f`
`=>W_f=DeltaPE-DeltaKE`

Inserting calculated values we get
`=>W_f=300h-956.57` `J`

Insert the value of height `h` (not given in the problem) to calculate the final answer