Block A has a weight of `300 N` and block B has a weight of `50 N`. Coefficient of friction for A is `mu_(k) = 0.2`. Determine the speed of block A after moves `1`m down the plane, starting from rest. Negelect the mass of the cord and pulleys.

Answer

A, B

Explanation

If A moves 1 m down the plane and its speed is v, then B will move 2m upwards and its speed will be 2v,
.
Using the equation,
`E_(i) -E_(f) =Work done against friction
:`. 0-[1/2 xx 30 xx v^(2) + 1/2 xx 5 xx (2v)^(2)`
`+ 5 xx 10 xx 2- 30 xx10 xx3/5]`
`=0.2 xx 30 xx 10 xx 4/5 xx1`
Solving this equation we get,
`v = 1.12 m//s