Question:medium

A man of mass 60 kg is standing in a lift moving up with a retardation of \( 2.8 \, \text{ms}^{-2} \). The apparent weight of the man is

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Acceleration direction is key. - Moving up, speeding up \(\to\) \( a \) up \(\to N = m(g+a) \). - Moving up, slowing down \(\to\) \( a \) down \(\to N = m(g-a) \).
Updated On: Mar 30, 2026
  • 756 N
  • 168 N
  • 588 N
  • 420 N
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The Correct Option is D

Solution and Explanation

Step 1: Understanding the Concept:
The apparent weight is the normal reaction force \( N \). The lift is moving up but retarding (slowing down), which means the acceleration vector points downwards. Acceleration \( a = 2.8 \, \text{m/s}^2 \) (downwards).
Step 2: Key Formula or Approach:
For a lift with downward acceleration \( a \): \[ N = m(g - a) \] (Note: "Moving up with retardation" is equivalent to downward acceleration).
Step 3: Detailed Explanation:
Given: Mass \( m = 60 \, \text{kg} \). Gravity \( g = 9.8 \, \text{m/s}^2 \) (standard assumption unless specified 10). Acceleration \( a = 2.8 \, \text{m/s}^2 \). Calculate \( N \): \[ N = 60 (9.8 - 2.8) \] \[ N = 60 (7) \] \[ N = 420 \, \text{N} \]
Step 4: Final Answer:
The apparent weight is 420 N.
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