Q. No.A block of mass M is hanging over a smooth and light pulley through a light string. The other end of the string is pulled by a constant force F. The kinetic energy of the block increases by 20 J in 1 s.
1. The tension in the string is Mg
2. The tension in the string is F
3. The work done by the tension on the block is 20 J in the above 1 s
4. The work done by the force of gravity is –20 J in tie above 1 s
A bullet hits a block kept at rest on a smooth horizontal surface and gets embedded into it. Which of the following does not change?
| 1. | linear momentum of the block |
| 2. | kinetic energy of the block |
| 3. | gravitational potential energy of the block |
| 4. | temperature of the block |
A ball kept in a closed box moves in the box making collisions with the walls. The box is kept on a smooth surface. The velocity of the centre of mass:
| 1. | of the box remains constant. |
| 2. | of the box plus the ball system remains constant. |
| 3. | of the ball remains constant. |
| 4. | of the ball relative to the box remains constant. |
A body at rest breaks into two pieces of equal masses. The parts will move:
| 1. | in the same direction. |
| 2. | along different lines. |
| 3. | in opposite directions with equal speeds. |
| 4. | in opposite directions with unequal speeds. |
The quantities remaining constant in a collision are:
| 1. | momentum, kinetic energy and temperature |
| 2. | momentum and kinetic energy but not temperature |
| 3. | momentum and temperature but not kinetic energy |
| 4. | momentum, but neither kinetic energy nor temperature |
In an elastic collision:
| 1. | the initial kinetic energy is equal to the final kinetic energy. |
| 2. | the final kinetic energy is less than the initial kinetic energy. |
| 3. | the kinetic energy remains constant. |
| 4. | the kinetic energy first increases then decreases. |
In an inelastic collision:
| 1. | the initial kinetic energy is equal to the final kinetic energy. |
| 2. | the final kinetic energy is less than the initial kinetic energy. |
| 3. | the kinetic energy remains constant. |
| 4. | the kinetic energy first increases and then decreases. |
A block moving in air breaks into two parts and the parts separate:
| (a) | the total momentum must be conserved |
| (b) | the total kinetic energy must be conserved |
| (c) | the total momentum must change |
| (d) | the total kinetic energy must change |
Choose the correct option from the given ones:
| 1. | (a) and (b) only |
| 2. | (a) and (c) only |
| 3. | (a) and (d) only |
| 4. | All of these |
In an elastic collision:
| (a) | The kinetic energy remains constant. |
| (b) | The linear momentum remains constant. |
| (c) | The final kinetic energy is equal to the initial kinetic energy. |
| (d) | The final linear momentum is equal to the initial linear momentum. |
Select the correct option from the choices provided:
| 1. | (a), (b) and (c) |
| 2. | (b), (c) and (d) |
| 3. | (a), (c) and (d) |
| 4. | none of these |
A ball hits a floor and rebounds after an inelastic collision. In this case:
| (a) | the momentum of the ball just after the collision is same as that just before the collision |
| (b) | the mechanical energy of the ball remains the same during the collision |
| (c) | the total momentum of the ball and the earth is conserved |
| (d) | the total energy of the ball and the earth remains the same |
Choose the correct options from the given ones:
| 1. | (a) and (b) only |
| 2. | (b) and (c) only |
| 3. | (c) and (d) only |
| 4. | none of these |
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