JEE MainPhysicsLaws of MotionNumerical+4 / −1
A person standing on a spring balance inside a stationary lift measures 60 kg. The weight of that person if the lift descends with uniform downward acceleration of 1.8 m/s2 will be N. [g = 10 m/s2]
Numerical answer
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Correct answer: 492
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Interpret the spring balance reading in the stationary lift
When the lift is stationary, the spring balance reads the person's apparent mass as .
Hence the actual mass of the person is
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Find the actual weight of the person
Actual weight is
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Lift descending with downward acceleration
If the lift accelerates downward with acceleration , then the apparent weight (normal reaction by the spring balance) becomes
Substituting the values:
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Final answer
Therefore, the weight measured in the descending lift is
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