A block A can slide on a frictionless incline of angle `theta` and length l, kept inside an elevator going up with uniform velocity v. Find the time taken by the block to slide down the length of the incline if it is released from the top of the incline.

Answer

A, B

Explanation

The driving force on the block whch makes the body to move down the plane is,
`F=mg sin theta `
` :. Acceleration = g sin theta`
Initial velocity of block, u=0
S=l
`a= g sin theta `
Now, ` S= ut+1/2at^2`
`rarr l=0+1/2(g sin theta)t^2`
` rarr t^2 = (2l)/(g sin theta)`
` rarr Time taken, `t= (2l)/(g sin theta`.