A) 800 N
B) 1200 N
C) zero
D) 400 N
Correct Answer: B
Solution :
Key Idea: When lift is moving upwards, it weighs more than actual weight of man by a factor of ma. Mass of man\[M=80\text{ }kg\] Acceleration of lift, \[a=5\text{ }m/{{s}^{2}}\] When lift is moving upwards, the reading of weighting scale will be equal to R. The equation of motion gives \[R-mg=ma\] or \[R=mg+ma=m(g+a)\] \[R=80(10+5)=80\times 15=1200\text{ }N\]You need to login to perform this action.
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