Question

A string of length 'l' fixed at one end carries a mass 'm' at the other end. The string makes `3/pi` revolutions/second around the vertical axis through the fixed end as shown in figure. The tension 'T' in the string is ______.

Options

• 36 ml

• 3 ml

• 18 ml

• 9 ml

Answer 1

A string of length 'l' fixed at one end carries a mass 'm' at the other end. The string makes `3/pi` revolutions/second around the vertical axis through the fixed end as shown in figure. The tension 'T' in the string is 36 ml.

Explanation:

The horizontal component of the tension, T sin θ provides the centripetal force.

∴ T sinθ = mrω²

r = l sinθ

∴ T sinθ = mω² l sinθ

∴ T = m ω² l

`omega = 2pif=2pi3/pi=6`

∴ ω² = 36

∴ T = 36 ml