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A person of mass $60$ kg stands on a weighing scale in a lift. The lift accelerates upward at $2$ m/s². What is the reading on the scale? (Take $g = 10$ m/s²)
A$480$ N
B$600$ N
C$720$ N
D$840$ N
Answer & Solution
Correct answer: C. $720$ N
The scale reads the normal reaction $N$. Newton's second law along the vertical: $N - mg = ma$, so $N = m(g + a) = 60 \times (10 + 2) = 720$ N.
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