In the below figure, what constant force 'P' is requried to bring the `50 kg` body, which starts from rest to a velocity of `10 m//s` in moving `7 m` along the plane ? (Neglect friction).
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Explanation

Work done by force P in displacing the block by
`7m , W_(1) = (F cos theta) (S)`
`W_(1) = (P cos 30^(2))7 = (7sqrt3)/2 PJ,`
`W_(2) = - mgh = - 50 xx 9.8 xx 7 sin 30^(@) = - 1715 J`
According to work energy theorem
`W_(1) + W_(2) = 1/2 m(v_(2)^(2) - v_(1)^(2))`
`(7 sqrt3 )/(2) P - 1715 = 1/2 xx 50 xx(10^(2) - 0^(2) ) Rightarrow P = 607 N`