A bead of mass 400 g is moving along a strai | vedclass

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(C) Given: Mass $m = 400 \ g = 0.4 \ kg$,Power $P = 1.2 \ W$,Time $t = 6 \ s$,Initial velocity $u = 0 \ m \ s^{-1}$.Work done by the force is given by

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(C) Given: Mass $m = 400 \ g = 0.4 \ kg$,Power $P = 1.2 \ W$,Time $t = 6 \ s$,Initial velocity $u = 0 \ m \ s^{-1}$.Work done by the force is given by $W = P 	imes t$.$W = 1.2 	imes 6 = 7.2 \ J$.According to the work-energy theorem,the work done by the force is equal to the change in kinetic energy of the bead.$W = \Delta K.E. = \frac{1}{2} m v^2 - \frac{1}{2} m u^2$.Since $u = 0$,$W = \frac{1}{2} m v^2$.$7.2 = \frac{1}{2} 	imes 0.4 	imes v^2$.$7.2 = 0.2 	imes v^2$.$v^2 = \frac{7.2}{0.2} = 36$.$v = \sqrt{36} = 6 \ m \ s^{-1}$.

$A$ bead of mass $400 \ g$ is moving along a straight line under a force that delivers a constant power $1.2 \ W$ to the bead. If the bead is initially at rest,the speed it attains after $6 \ s$ in $m \ s^{-1}$ is:

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