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Hi guys,
Can someone please clear up this confusion for me?
45. Compare the work done by gravity on the block for each of the three ways of lifting the block.
A) I is largest
B) II is largest
C) III is largest
D) The work done by gravity is the same in all cases
Ans: D, The work done by gravity is the same in all cases.
The passage has a picture which would be difficult to reproduce here, but the scenario is that we have platform with height h onto which a box is being lifted (case I), platform with height h with an incline of 60 deg and platform with height h with an inclide of 30 deg. In each case we are lifitng a box onto a platform. We have to compare the work done by gravity on the block for each of three ways of lifitng the block.
So we have Wdone by lifter - Wdone by gravity = mgh. Correct? Yes, PEf = mgh, but to get to this point, work done by lifter and work done by gravity vary because of distance of incline, right? How can we assume right away that the work done by gravity is the same in all cases, don't we have to account for the work done by lifter (which varies, depending on the angle of inclination)?
Can someone please clear up this confusion for me?
45. Compare the work done by gravity on the block for each of the three ways of lifting the block.
A) I is largest
B) II is largest
C) III is largest
D) The work done by gravity is the same in all cases
Ans: D, The work done by gravity is the same in all cases.
The passage has a picture which would be difficult to reproduce here, but the scenario is that we have platform with height h onto which a box is being lifted (case I), platform with height h with an incline of 60 deg and platform with height h with an inclide of 30 deg. In each case we are lifitng a box onto a platform. We have to compare the work done by gravity on the block for each of three ways of lifitng the block.
So we have Wdone by lifter - Wdone by gravity = mgh. Correct? Yes, PEf = mgh, but to get to this point, work done by lifter and work done by gravity vary because of distance of incline, right? How can we assume right away that the work done by gravity is the same in all cases, don't we have to account for the work done by lifter (which varies, depending on the angle of inclination)?