A stone of mass 1 kg is tied at one end of a string of length 1 m . It is whirled in a vertical circle at a constant speed of 4 m s- 1 . The tension in the string is 6 N when the stone is at (.g=10 m s- 2.)

Question

A stone of mass 1 kg is tied at one end of a string of length 1 m . It is whirled in a vertical circle at a constant speed of 4 m s- 1 . The tension in the string is 6 N when the stone is at (.g=10 m s- 2.) (A) Top of the circle (B) Bottom of the circle (C) Half way down (D) None of these

Tardigrade Admin · Accepted Answer

When the string makes an angle θ with the vertical, then T-mgcosθ =(m v2/r) Substituting the values, we obtain 6 - (1) (1 0) textcos θ = (42 text. 1/1) = 16 textcos θ = - 1 θ = 1 8 0 texto

Q. A stone of mass $1 k g$ is tied at one end of a string of length $1 m$ . It is whirled in a vertical circle at a constant speed of $4 m s^{- 1}$ . The tension in the string is $6 N$ when the stone is at $(g = 10 m s^{- 2})$

Top of the circle

Bottom of the circle

Half way down

None of these

When the string makes an angle $θ$ with the vertical, then
$T - m g cos θ = \frac{m v ^{2}}{r}$
Substituting the values, we obtain
$6 - (1) (10) cos θ = \frac{4 ^{2} . 1}{1}$ = 16
$cos θ = - 1$
$θ = 18 0^{o}$

Q. A stone of mass 1kg is tied at one end of a string of length 1m . It is whirled in a vertical circle at a constant speed of 4ms−1 . The tension in the string is 6N when the stone is at (g=10ms−2)