STANDARDPhysics-Laws of Motion
STANDARD Physics Normal Force MCQ Question
Type: MCQ-conceptual-Medium-Class 11
A person of mass 50 kg stands on a weighing scale on a lift. If the lift is ascending upwards with a uniform acceleration of 9 m s⁻², what would be the reading of the weighing scale? (Take g = 10 m s⁻²)
A
50 kg
B
60 kg
C
95 kg
D
100 kg
Correct Answer
Option C
Detailed Explanation
The reading on the scale is a measure of the force on the floor by the person. By Newton's third law, this is equal and opposite to the normal force N on the person by the floor. When the lift is ascending upwards with an acceleration of 9 m s⁻², then N = 50 × 10 + 50 × 9 = 50(10 + 9) = 950 N. The reading of the weighing machine is 95 kg.
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