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A person of 60 kg descends in a lift wit...

A person of 60 kg descends in a lift with an acceleration `2 m s^(-2).` The cable of lift suddenly breaks down. The weight of the person inside the lift is

A

60 g

B

zero

C

62 g

D

58 g

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The correct Answer is:
To solve the problem, we need to determine the weight of a person inside a lift that suddenly breaks down. The person has a mass of 60 kg and is initially descending with an acceleration of 2 m/s². ### Step-by-Step Solution: 1. **Understanding Weight and Apparent Weight**: - The weight of an object is given by the formula: \[ W = mg \] where \( m \) is the mass of the object and \( g \) is the acceleration due to gravity (approximately \( 9.8 \, \text{m/s}^2 \)). - The apparent weight (normal force, \( N \)) experienced by the person in the lift is affected by the acceleration of the lift. 2. **Calculating the Weight of the Person**: - The actual weight of the person is: \[ W = 60 \, \text{kg} \times 9.8 \, \text{m/s}^2 = 588 \, \text{N} \] 3. **Setting Up the Free Body Diagram**: - When the lift is descending with an acceleration of \( 2 \, \text{m/s}^2 \), we can analyze the forces acting on the person: - Downward force: \( mg \) (weight) - Upward force: \( N \) (normal force or apparent weight) 4. **Applying Newton's Second Law**: - According to Newton's second law, the net force acting on the person can be written as: \[ F_{\text{net}} = ma \] - Taking downward as positive, we have: \[ mg - N = ma \] - Rearranging gives: \[ N = mg - ma \] 5. **Substituting Values**: - Substitute \( m = 60 \, \text{kg} \), \( g = 9.8 \, \text{m/s}^2 \), and \( a = 2 \, \text{m/s}^2 \): \[ N = (60 \, \text{kg} \times 9.8 \, \text{m/s}^2) - (60 \, \text{kg} \times 2 \, \text{m/s}^2) \] \[ N = 588 \, \text{N} - 120 \, \text{N} = 468 \, \text{N} \] 6. **Condition When the Lift Breaks**: - When the lift suddenly breaks, it is in free fall. In this case, the acceleration of the lift becomes equal to the acceleration due to gravity (\( g \)). - Therefore, the apparent weight becomes: \[ N = mg - mg = 0 \] ### Final Answer: - The weight of the person inside the lift when it suddenly breaks is **0 N**. This indicates that the person experiences weightlessness.

To solve the problem, we need to determine the weight of a person inside a lift that suddenly breaks down. The person has a mass of 60 kg and is initially descending with an acceleration of 2 m/s². ### Step-by-Step Solution: 1. **Understanding Weight and Apparent Weight**: - The weight of an object is given by the formula: \[ W = mg ...
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