02. Torque, Angular Momentum
Rotational Motion

149951 An electric motor of power \(75 \mathrm{~W}\) rotates a flywheel of moment of inertia \(0.36 \mathrm{kgm}^{2}\) at a constant rate of \(100 \mathrm{rads}^{-1}\). If the power is switched off, the time taken for the wheel to come to rest is

1 \(12 \mathrm{~s}\)
2 \(24 \mathrm{~s}\)
3 \(36 \mathrm{~s}\)
4 \(48 \mathrm{~s}\)
Rotational Motion

149952 A flywheel of mass \(1 \mathrm{~kg}\) and radius vector \((2 \hat{i}+\hat{\mathbf{j}}+2 \hat{\mathbf{k}}) \mathbf{m}\) is at rest. When a force \((3 \hat{i}+2 \hat{j}-4 \hat{k}) \quad N\) acts on it tangentially, it can rotate freely. Then, its angular velocity after \(4.5 \mathrm{~s}\) is

1 \(\frac{2}{9} \sqrt{261} \mathrm{rads}^{-1}\)
2 \(\frac{3}{2} \sqrt{261} \operatorname{rads}^{-1}\)
3 \(\sqrt{261} \mathrm{rads}^{-1}\)
4 \(\frac{5}{9} \sqrt{261} \mathrm{rad} \mathrm{s}^{-1}\)
Rotational Motion

149953 A particle \(P\) is moving uniformly along a straight line as shown in the figure. During the motion of the particle from \(A\) to \(B\), the angular momentum of the particle about \(O\) :

1 Increase
2 Decrease
3 Remains constant
4 First increase then decrease
Rotational Motion

149955 The distance between Sun and Earth is \(1.6 \times\)
\(10^{11} \mathrm{~m}\) and the radius of Earth is \(6.4 \times 10^{6} \mathrm{~m}\). The ratio of the angular momentum of Earth around the Sun to the angular momentum around its own axis is approximately (Assume Earth as a solid sphere with uniform mass density and rotates around the Sun in a circular path.)

1 \(2.0 \times 10^{2}\)
2 \(5.1 \times 10^{8}\)
3 \(4.3 \times 10^{6}\)
4 \(8.7 \times 10^{12}\)
Rotational Motion

149956 If a rolling body's angular momentum changes
by 20 SI units in 3 seconds, by a constant torque. Then find the torque on the body

1 \(20 / 3\) SI units
2 \(100 / 3\) SI units
3 20 SI units
4 5 SI units
Rotational Motion

149951 An electric motor of power \(75 \mathrm{~W}\) rotates a flywheel of moment of inertia \(0.36 \mathrm{kgm}^{2}\) at a constant rate of \(100 \mathrm{rads}^{-1}\). If the power is switched off, the time taken for the wheel to come to rest is

1 \(12 \mathrm{~s}\)
2 \(24 \mathrm{~s}\)
3 \(36 \mathrm{~s}\)
4 \(48 \mathrm{~s}\)
Rotational Motion

149952 A flywheel of mass \(1 \mathrm{~kg}\) and radius vector \((2 \hat{i}+\hat{\mathbf{j}}+2 \hat{\mathbf{k}}) \mathbf{m}\) is at rest. When a force \((3 \hat{i}+2 \hat{j}-4 \hat{k}) \quad N\) acts on it tangentially, it can rotate freely. Then, its angular velocity after \(4.5 \mathrm{~s}\) is

1 \(\frac{2}{9} \sqrt{261} \mathrm{rads}^{-1}\)
2 \(\frac{3}{2} \sqrt{261} \operatorname{rads}^{-1}\)
3 \(\sqrt{261} \mathrm{rads}^{-1}\)
4 \(\frac{5}{9} \sqrt{261} \mathrm{rad} \mathrm{s}^{-1}\)
Rotational Motion

149953 A particle \(P\) is moving uniformly along a straight line as shown in the figure. During the motion of the particle from \(A\) to \(B\), the angular momentum of the particle about \(O\) :

1 Increase
2 Decrease
3 Remains constant
4 First increase then decrease
Rotational Motion

149955 The distance between Sun and Earth is \(1.6 \times\)
\(10^{11} \mathrm{~m}\) and the radius of Earth is \(6.4 \times 10^{6} \mathrm{~m}\). The ratio of the angular momentum of Earth around the Sun to the angular momentum around its own axis is approximately (Assume Earth as a solid sphere with uniform mass density and rotates around the Sun in a circular path.)

1 \(2.0 \times 10^{2}\)
2 \(5.1 \times 10^{8}\)
3 \(4.3 \times 10^{6}\)
4 \(8.7 \times 10^{12}\)
Rotational Motion

149956 If a rolling body's angular momentum changes
by 20 SI units in 3 seconds, by a constant torque. Then find the torque on the body

1 \(20 / 3\) SI units
2 \(100 / 3\) SI units
3 20 SI units
4 5 SI units
Rotational Motion

149951 An electric motor of power \(75 \mathrm{~W}\) rotates a flywheel of moment of inertia \(0.36 \mathrm{kgm}^{2}\) at a constant rate of \(100 \mathrm{rads}^{-1}\). If the power is switched off, the time taken for the wheel to come to rest is

1 \(12 \mathrm{~s}\)
2 \(24 \mathrm{~s}\)
3 \(36 \mathrm{~s}\)
4 \(48 \mathrm{~s}\)
Rotational Motion

149952 A flywheel of mass \(1 \mathrm{~kg}\) and radius vector \((2 \hat{i}+\hat{\mathbf{j}}+2 \hat{\mathbf{k}}) \mathbf{m}\) is at rest. When a force \((3 \hat{i}+2 \hat{j}-4 \hat{k}) \quad N\) acts on it tangentially, it can rotate freely. Then, its angular velocity after \(4.5 \mathrm{~s}\) is

1 \(\frac{2}{9} \sqrt{261} \mathrm{rads}^{-1}\)
2 \(\frac{3}{2} \sqrt{261} \operatorname{rads}^{-1}\)
3 \(\sqrt{261} \mathrm{rads}^{-1}\)
4 \(\frac{5}{9} \sqrt{261} \mathrm{rad} \mathrm{s}^{-1}\)
Rotational Motion

149953 A particle \(P\) is moving uniformly along a straight line as shown in the figure. During the motion of the particle from \(A\) to \(B\), the angular momentum of the particle about \(O\) :

1 Increase
2 Decrease
3 Remains constant
4 First increase then decrease
Rotational Motion

149955 The distance between Sun and Earth is \(1.6 \times\)
\(10^{11} \mathrm{~m}\) and the radius of Earth is \(6.4 \times 10^{6} \mathrm{~m}\). The ratio of the angular momentum of Earth around the Sun to the angular momentum around its own axis is approximately (Assume Earth as a solid sphere with uniform mass density and rotates around the Sun in a circular path.)

1 \(2.0 \times 10^{2}\)
2 \(5.1 \times 10^{8}\)
3 \(4.3 \times 10^{6}\)
4 \(8.7 \times 10^{12}\)
Rotational Motion

149956 If a rolling body's angular momentum changes
by 20 SI units in 3 seconds, by a constant torque. Then find the torque on the body

1 \(20 / 3\) SI units
2 \(100 / 3\) SI units
3 20 SI units
4 5 SI units
Rotational Motion

149951 An electric motor of power \(75 \mathrm{~W}\) rotates a flywheel of moment of inertia \(0.36 \mathrm{kgm}^{2}\) at a constant rate of \(100 \mathrm{rads}^{-1}\). If the power is switched off, the time taken for the wheel to come to rest is

1 \(12 \mathrm{~s}\)
2 \(24 \mathrm{~s}\)
3 \(36 \mathrm{~s}\)
4 \(48 \mathrm{~s}\)
Rotational Motion

149952 A flywheel of mass \(1 \mathrm{~kg}\) and radius vector \((2 \hat{i}+\hat{\mathbf{j}}+2 \hat{\mathbf{k}}) \mathbf{m}\) is at rest. When a force \((3 \hat{i}+2 \hat{j}-4 \hat{k}) \quad N\) acts on it tangentially, it can rotate freely. Then, its angular velocity after \(4.5 \mathrm{~s}\) is

1 \(\frac{2}{9} \sqrt{261} \mathrm{rads}^{-1}\)
2 \(\frac{3}{2} \sqrt{261} \operatorname{rads}^{-1}\)
3 \(\sqrt{261} \mathrm{rads}^{-1}\)
4 \(\frac{5}{9} \sqrt{261} \mathrm{rad} \mathrm{s}^{-1}\)
Rotational Motion

149953 A particle \(P\) is moving uniformly along a straight line as shown in the figure. During the motion of the particle from \(A\) to \(B\), the angular momentum of the particle about \(O\) :

1 Increase
2 Decrease
3 Remains constant
4 First increase then decrease
Rotational Motion

149955 The distance between Sun and Earth is \(1.6 \times\)
\(10^{11} \mathrm{~m}\) and the radius of Earth is \(6.4 \times 10^{6} \mathrm{~m}\). The ratio of the angular momentum of Earth around the Sun to the angular momentum around its own axis is approximately (Assume Earth as a solid sphere with uniform mass density and rotates around the Sun in a circular path.)

1 \(2.0 \times 10^{2}\)
2 \(5.1 \times 10^{8}\)
3 \(4.3 \times 10^{6}\)
4 \(8.7 \times 10^{12}\)
Rotational Motion

149956 If a rolling body's angular momentum changes
by 20 SI units in 3 seconds, by a constant torque. Then find the torque on the body

1 \(20 / 3\) SI units
2 \(100 / 3\) SI units
3 20 SI units
4 5 SI units
Rotational Motion

149951 An electric motor of power \(75 \mathrm{~W}\) rotates a flywheel of moment of inertia \(0.36 \mathrm{kgm}^{2}\) at a constant rate of \(100 \mathrm{rads}^{-1}\). If the power is switched off, the time taken for the wheel to come to rest is

1 \(12 \mathrm{~s}\)
2 \(24 \mathrm{~s}\)
3 \(36 \mathrm{~s}\)
4 \(48 \mathrm{~s}\)
Rotational Motion

149952 A flywheel of mass \(1 \mathrm{~kg}\) and radius vector \((2 \hat{i}+\hat{\mathbf{j}}+2 \hat{\mathbf{k}}) \mathbf{m}\) is at rest. When a force \((3 \hat{i}+2 \hat{j}-4 \hat{k}) \quad N\) acts on it tangentially, it can rotate freely. Then, its angular velocity after \(4.5 \mathrm{~s}\) is

1 \(\frac{2}{9} \sqrt{261} \mathrm{rads}^{-1}\)
2 \(\frac{3}{2} \sqrt{261} \operatorname{rads}^{-1}\)
3 \(\sqrt{261} \mathrm{rads}^{-1}\)
4 \(\frac{5}{9} \sqrt{261} \mathrm{rad} \mathrm{s}^{-1}\)
Rotational Motion

149953 A particle \(P\) is moving uniformly along a straight line as shown in the figure. During the motion of the particle from \(A\) to \(B\), the angular momentum of the particle about \(O\) :

1 Increase
2 Decrease
3 Remains constant
4 First increase then decrease
Rotational Motion

149955 The distance between Sun and Earth is \(1.6 \times\)
\(10^{11} \mathrm{~m}\) and the radius of Earth is \(6.4 \times 10^{6} \mathrm{~m}\). The ratio of the angular momentum of Earth around the Sun to the angular momentum around its own axis is approximately (Assume Earth as a solid sphere with uniform mass density and rotates around the Sun in a circular path.)

1 \(2.0 \times 10^{2}\)
2 \(5.1 \times 10^{8}\)
3 \(4.3 \times 10^{6}\)
4 \(8.7 \times 10^{12}\)
Rotational Motion

149956 If a rolling body's angular momentum changes
by 20 SI units in 3 seconds, by a constant torque. Then find the torque on the body

1 \(20 / 3\) SI units
2 \(100 / 3\) SI units
3 20 SI units
4 5 SI units