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A block of mass 10kg is released on a fi...

A block of mass `10kg` is released on a fixed wedge inside a cart which is moved with constant velocity `10m//s` towards right. Take initial velocity of block with respect to cart zero. Then work done by normal reaction (with respect to ground) on block in two second will be `:(g=10 m//s^(2))`.

A

zero

B

`960J`

C

`1200J`

D

none of these

Text Solution

Verified by Experts

The correct Answer is:
B
Because the acceleration of wedge is zero , the normal reaction exerted by wedge on block is `N=mg cos 37^(@)`.
The acceleration of the block is `g sin 37^(@)` along the incline and initial velocity of the block is `v=10m//s` horizontally towards right as shown in figure.

The component of velocity of the block normal to the incline is `v sin 37^(@)` . Hence the displacement of the block normal to the incline in `t=2` second is
`S=v sin 37^(@)xx2=10xx(3)/(5)xx2=12m`.
`:.` The work done by normal reaction
`W=mg cos 37^(@) , S=100xx(4)/(5)xx12=960J`
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