Q58 of 146 Page 147

If 784 J of work was done in lifting a 20 kg mass, calculate the height through which it was lifted. (g = 9.8 m/s2)

Mass of a body = 20kg

Acceleration due to gravity (g) = 9.8m/s2


Work done = 784 J


As we know,


W = m x g x h


h = W/m x g


h = 784/ 20 x 9.8


h = 784/196


h = 4m


Therefore, the height through which the body was lifted is 4m


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A car is accelerated on a leveled road and attains a speed of 4 times its initial speed. In this process, the kinetic energy of the car:

A. Does not change


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