A block of mass 2.0 kg kept at rest on an inclined plane of inclination `37^0` is pulled up the plane by applying a constant force of 20 N parallel to the incline. The force acts for one second. A. show that the work done by the applied force does not exceed 40 J.

Answer

A, B, C, D

Explanation

a. `m=2kg, theta=37^0 F=20N`
From the free body diagram
`F=(2gsintheta)+ma`
`rarr a=(20-20sintheta)/2=4m/sec^2`
`s=ut+1/2at^2=2m`
`(u=0, t=1s, a=1.66)`
So,workdone `W=FS=20xx2=40J`

b. If W=40J
`S=W/F=40/20=2m`
So, work done `W=-mgh`
`=020xx1.5=-24J`
c. `v=u+at`
`=4xx1=4m/sec`
So, `K.E. =1/2mv^2`
`=1/22xx16=6J`