18. [Ipt A person pushes a block along a level floor with a small, non-zero coef

Question

18. [Ipt A person pushes a block along a level floor with a small, non-zero coefficient of friction at constant speed. The work done by the person__ A) is zero B) is less than zero C) is greater than zero D) could be (+) or (-depending upon coordinate system Submit All Answers 9.[lpt Two boxes that are the same size need to be stacked on top of each other. Their masses are 10 kg and 30 kg, respectively. In which case will you do more work? A) 10 kg on top B) 30 kg on top C) not enough information D) equal work for both ways Submit All Answers

Explanation / Answer

1) according to work energy theorem,

workdone = change in kinetic energy= 1/2 mv^2- 1/2mU^2

since the speed is constant... then v=u

therfore workdone is done

ans :-A

2) according to the given problem , the two masses are one another...but not moving

since work= force * dispacement

here no value of displacement given ...hence there is no workdone...

so not enough information is given to find workdone

ans:- c

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