A block of mass `10 kg` is released on a fixed wedge inside a cart which is moving with constant velocity `10 ms^(1)` towards right. There is no relative motion between block and cart. Then work done by mormal reaction on block in two seconds from ground frame will be (g=10 ms^(1))

Options

A. `1320 J`
B. `960 J`
C. `1200 J`
D. `240 J`

Answer

B

Explanation

Constant velocity means net force `= 0`
Using Lami's theorem in the figure,
.
We have,
`N/(sin (18o^@-53^@)) =(100)/(sin 90^@)`
`:. N=100 sin 53^@ =80 N`
Now, `W_(N) =NS cos 53^@`
`=(80)(20)(0.6)`
`=960 J`.