Which of the diagrams shown in the figure represents the variation of to mechanical energy of a pendulum oscillating in the air as a function of time.
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3. | 4. |
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3. | 4. |
A man of mass \(m,\) standing at the bottom of the staircase, of height \(L,\) climbs it and stands at its top.
(a) | work done by all forces on man is equal to the rise in potential energy \(mgL.\) |
(b) | work done by all forces on man is zero. |
(c) | work done by the gravitational force on man is \(mgL.\) |
(d) | the reaction force from a step does no work because the point of the application of the force does not move while the force exists. |
Choose the correct option:
1. (a), (d)
2. (a), (c)
3. (b), (d)
4. (a), (b), (c)
A bullet of mass \(m\) fired at \(30^\circ\) to the horizontal leaves the barrel of the gun with a velocity \(v.\) The bullet hits a soft target at a height \(h\) above the ground while it is moving downward and emerge out with half the kinetic energy it had before hitting the target. Consider the following statements.
(a) | the velocity of the bullet will be reduced to half its initial value. |
(b) | the velocity of the bullet will be more than half of its earlier velocity. |
(c) | the bullet will continue to move along the same parabolic path. |
(d) | the bullet will move in a different parabolic path. |
(e) | the bullet will fall vertically downward after hitting the target. |
(f) | the internal energy of the particles of the target will increase. |
Which of the above-given statement(s) is/are correct in respect of the bullet after it emerges out of the target?
1. (a), (c), (f)
2. (a), (d), (f)
3. (b), (d, (f)
4. (a), (b), (c)