Consider an elliptically shaped rail PQ in the vertical plane with O P = 3 m and O Q = 4 m . A block of mass…

Consider an elliptically shaped rail PQ in the vertical plane with OP = 3 m and OQ = 4 m . A block of mass 1 kg is pulled along the rail from P to Q with a force of 18 N, which is always parallel to line PQ (see the figure given). Assuming no frictional losses, the kinetic energy of the block when it reaches Q is (n×10) Joules. The value of n is (take acceleration due to gravity = 10 ms2 )

Solution

Using work energy theorem
Wmg+WF=KE
-mgh+Fd=KE
-1×10×4+185=KE
KE=50
n=5 !

Asked in: JEE Advanced 2014 (Paper 1)

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