A) 80 J, -45 J
B) 40 J, 35 J
C) zero, 0.25 J
D) 80 J,-40 J
Correct Answer: D
Solution :
Weight \[mg=2\times 10=20N\] Work done by the applied force \[{{W}_{F}}=Fh\cos {{0}^{o}}.\] As the angle between force and displacement is \[{{\text{0}}^{\text{o}}}\text{,}\] therefore or \[{{\text{W}}_{F}}=40\times 2\times 1=80\,J\] Similarly, work done by its weight \[{{W}_{mg}}=mg\times h\times \cos {{180}^{o}}\] \[=20\times 2\times -1=-40\,J\]
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