Masses of 3 kg and 5 kg hang from a light string over a smooth pulley (g = 10 m/s^2). What is the tension in the string?
Answer and explanation
Correct answer: C. 37.5 N
- Step 1: The acceleration is a = (m2 - m1) g / (m1 + m2) = 2.5 m/s^2.
- Step 2: For the lighter mass, T = m1 (g + a) = 3 x (10 + 2.5) = 37.5 N.
Answer
37.5 N.
Why not the others: '30 N' is the weight of the lighter mass alone; '50 N' is the weight of the heavier mass alone; '40 N' is the average of the two weights.
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