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WORK – ———————————–?
A body mass 0.20 kilograms slip by track in the form of a semicircle of radius R = 4.0 meters starting from point A. When passing through the lowest point B the speed is 6.0 m / s. In section AB the work of the forces resisting motion is ?
Figure on the link: img130.image shack.us/img130/8563/imagemds.png (Please remove spaces from link)
work done on the body by resistive forces is W = m g r – 1 / m v^2 = 0.2×9.8×4 – 1/2 x0.2 x 36
= 6 J ( nearly)
( it is by coservation of energy , that
work done = potential energy lost – kinetic energy gained )