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A locomotive of mass m starts moving so that its velocity varies according to the law `V=alphasqrts,` where `alpha` is a constant and s is the distance covered. Find the total work done by all the forces acting on the locomotive during the first t seconds after the beginning of motion. |
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Answer» Differentiating `v(s)` with respect to time `(dv)/(dt)=(a)/(2sqrts)(ds)/(dt)=(a)/(2sqrts)asqrts=a^2/2=w` (As locomative is in unidirectional motion) Hence force acting on the locomotive `F=mw=(ma^2)/(2)` Let, at `v=0` at `t=0` then the distance covered during the first t seconds `s=1/2wt^2=1/2a^2/2t^2=a^2/4t^2` Hence the sought work, `A=Fs=(ma^2)/(2)((a^2t^2))/(4)=(ma^4t^2)/(8)` |
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