If there is no external force acting on a non-rigid body which of the following quantities must remain constant?
a. | angular momentum |
b. | linear momentum |
c. | kinetic energy |
d. | moment of inertia |
1. | (a) and (b) |
2. | (b) and (c) |
3. | (c) and (d) |
4. | (a) and (d) |
A uniform rod of mass \(m\) and length \(L\) is struck at both ends by two particles of masses m, each moving with identical speeds \(u,\) but in opposite directions, perpendicular to its length. The particles stick to the rod after colliding with it. The system rotates with an angular speed:
1. | \(\dfrac{u}{L}\) | 2. | \(\dfrac{2u}{L}\) |
3. | \(\dfrac{12u}{7L}\) | 4. | \(\dfrac{6u}{L}\) |
A body is in pure rotation. The linear speed \(v\) of a particle, the distance \(r\) of the particle from the axis and the angular velocity \(\omega\) of the body are related as \(w=\dfrac{v}{r}\). Thus:
1. \(w\propto\dfrac{1}{r}\)
2. \(w\propto\ r\)
3. \(w=0\)
4. \(w\) is independent of \(r\)
Consider two uniform discs of the same thickness and different radii \(R_1=R\) and \(R_2=\alpha R\) made of the same material. If the ratio of their moments of inertia, \(I_1\) and\(I_2,\) respectively, about their axes is \(I_1:I_2=1:16,\)then the value of \(\alpha\) is:
1. \(\sqrt{2}\)
2. \(4\)
3. \(2\)
4. \(2\sqrt{2}\)
1. | \({\dfrac b 2}\) | 2. | \({ \dfrac b 4}\) |
3. | \({\dfrac b 8}\) | 4. | \(\dfrac b 3\) |
1. | \(\omega_0\) | 2. | \(2\omega_0\) |
3. | \(\dfrac32\omega_0\) | 4. | \(\dfrac52\omega_0\) |
A uniform rod of length \(200~ \text{cm}\) and mass \(500~ \text g\) is balanced on a wedge placed at \(40~ \text{cm}\) mark. A mass of \(2~\text{kg}\) is suspended from the rod at \(20~ \text{cm}\) and another unknown mass \(m\) is suspended from the rod at \(160~\text{cm}\) mark as shown in the figure. What would be the value of \(m\) such that the rod is in equilibrium? (Take \(g=10~( \text {m/s}^2)\)
1. | \({\dfrac 1 6}~\text{kg}\) | 2. | \({\dfrac 1 {12}}~ \text{kg}\) |
3. | \({\dfrac 1 2}~ \text{kg}\) | 4. | \({\dfrac 1 3}~ \text{kg}\) |