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Given: Mass (m) = 0.4 kg, frequency (n) = 2 rev/sec, radius (r) = 1.2 m. The linear velocity of the body (v) is calculated as ωr = (2πn)r. What is the tension in the string when the body is at the top of the circle?

1. mv²/r − mg
2. 0.4 × (15.08)²/2 − (0.4 × 9.8)
3. 45.78 − 3.92 = 41.56 N
4. Tension = mv²/r

Correct answer: 45.78 − 3.92 = 41.56 N

Solution

The tension at the top of the circle is given by T = mv²/r - mg. Substituting the values: m = 0.4 kg, v = ωr = (2π × 2) × 1.2 = 15.08 m/s, r = 1.2 m, and g = 9.8 m/s², we get T = 0.4 × (15.08)² / 1.2 - 0.4 × 9.8 = 45.78 - 3.92 = 41.56 N.

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