A circular disc is rotating about its own axis at uniform angular velocity ω. The disc is subjected to uniform angular retardation by which its angular velocity is decreased to ω/2 during 120 rotations. The number of rotations further made by it before coming to rest is

Question

A circular disc is rotating about its own axis at uniform angular velocity ω. The disc is subjected to uniform angular retardation by which its angular velocity is decreased to ω/2 during 120 rotations. The number of rotations further made by it before coming to rest is (A) 120 (B) 60 (C) 40 (D) 20

Tardigrade Admin · Accepted Answer

α is constant α = (ω12 - ω22/2 θ) (ω - ( (ω/2) )2 /2 θ1) = (( (ω/2))2 - 0/2θ2) θ2 = (θ1/3)

Q. A circular disc is rotating about its own axis at uniform angular velocity $ω .$ The disc is subjected to uniform angular retardation by which its angular velocity is decreased to $ω /2$ during 120 rotations. The number of rotations further made by it before coming to rest is

120

60

40

20

$α$ is constant
$α = \frac{ω _{1}^{2} - ω _{2}^{2}}{2 θ}$
$\frac{ω - ( \frac{ω}{2} ) ^{2}}{2 θ _{1}} = \frac{( \frac{ω}{2} ) ^{2} - 0}{2 θ _{2}}$
$θ_{2} = \frac{θ _{1}}{3}$

Q. A circular disc is rotating about its own axis at uniform angular velocity ω. The disc is subjected to uniform angular retardation by which its angular velocity is decreased to ω/2 during 120 rotations. The number of rotations further made by it before coming to rest is

120

60

40

20

α is constant α=2θω12​−ω22​​ 2θ1​ω−(2ω​)2​=2θ2​(2ω​)2−0​ θ2​=3θ1​​

Q. A circular disc is rotating about its own axis at uniform angular velocity $ω .$ The disc is subjected to uniform angular retardation by which its angular velocity is decreased to $ω /2$ during 120 rotations. The number of rotations further made by it before coming to rest is

$α$ is constant
$α = \frac{ω _{1}^{2} - ω _{2}^{2}}{2 θ}$
$\frac{ω - ( \frac{ω}{2} ) ^{2}}{2 θ _{1}} = \frac{( \frac{ω}{2} ) ^{2} - 0}{2 θ _{2}}$
$θ_{2} = \frac{θ _{1}}{3}$