A boy ties a stone of mass 100 g to the end of a 2 m long string and whirls it around in a horizontal plane. The string can withstand the maximum tension of 80 N. If the maximum speed with which the stone can revolve is ( K /π) rev . / min. The value of K is: (Assume the string is massless and unstretchable)

Question

A boy ties a stone of mass 100 g to the end of a 2 m long string and whirls it around in a horizontal plane. The string can withstand the maximum tension of 80 N. If the maximum speed with which the stone can revolve is ( K /π) rev . / min. The value of K is: (Assume the string is massless and unstretchable) (A) 400 (B) 300 (C) 600 (D) 800

Tardigrade Admin · Accepted Answer

T=M ω2 R T=80 N M=0.1 ω=? R=2 m 80=0.1 ω2(2) ω2=400 ω=20 2 π f =20 f =(10/π) ( rev / s ) =(600/π) ( rev / min )

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T=Mω2R T=80N M=0.1 ω=? R=2m 80=0.1ω2(2) ω2=400 ω=20 2πf=20 f=π10​srev​ =π600​minrev​

$T = M ω^{2} R$
$T = 80 N$
$M = 0.1$
$ω = ?$
$R = 2 m$
$80 = 0.1 ω^{2} (2)$
$ω^{2} = 400$
$ω = 20$
$2 π f = 20$
$f = \frac{10}{π} \frac{re v}{s}$
$= \frac{600}{π} \frac{re v}{m i n}$