The work done by all the forces (external and internal) on a system equals the change in:
1. | total energy | 2. | kinetic energy |
3. | potential energy | 4. | none of these |
A block of \(1\) kg is released from a top of a smooth curve AB, and then it encounters a rough surface BC, coming to rest at C. The work done by friction is: (\(g=10\) m/s2)
1. \(25\) J
2. \(50\) J
3. \(-25\) J
4. \(-50\) J
The minimum speed that a simple pendulum's bob should be given so that it rises to a level where its string makes \(60^\circ\) with the vertical is:
1. \(\sqrt{2gL}\)
2. \(\sqrt{2gL}\) \(cos 60^\circ\)
3. \(\sqrt{2g(L-L~cos60^\circ)}\)
4. \(\sqrt{2gL}\) \(sin 60^\circ\)
1. | \(\frac{\pi}{6}\) | 2. | \(\frac{\pi}{3}\) |
3. | \(\frac{\pi}{2}\) | 4. | \(\frac{2\pi}{3}\) |
1. | zero | 2. | \(-\frac12mu^2cos^2\theta\) |
3. | \(-\frac12mu^2sin^2\theta\) | 4. | \(-\frac12mu^2\) |