A man is standing on a weighing machine placed in a lift. When stationary, his mass is recorded as 40 kg. If the lift is moved upwards with an acceleration of 2ms-2, then the weight recorded in the machine will be: (g = 10 ms-2)
Correct answer: D. 48 kg
- A. 32 kg
- B. 40 kg
- C. 42 kg
- D. 48 kg
Explanation
To determine the apparent weight of the man when the lift is accelerating upwards, we use the formula for normal force (apparent weight) in an accelerating frame: N = m(g + a), where m is the mass, g is the acceleration due to gravity, and a is the acceleration of the lift. Given that m = 40 kg, g = 10 ms-2, and a = 2 ms-2, substituting these values gives: N = 40 (10 + 2) = 480 newton Since weight is typically expressed in kg-wt, we convert this to 48 kg-wt. Therefore, the correct answer is 48 kg. All other options either do not account for the lift's acceleration or miscalculate its effect, resulting in incorrect apparent weight values.
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