The total work done on a particle is equal to the change in its kinetic energy:
1. | always |
2. | only if the forces acting on it are conservative |
3. | only if gravitational force alone acts on it |
4. | only if elastic force alone acts on it |
1. | \(\sqrt{\dfrac{l F_{} \cos \theta}{m}}\) | 2. | \(\dfrac{2 l \mathrm{~F}_{} \cos \theta}{\mathrm{m}}\) |
3. | \(\sqrt{\dfrac{2 l}{m} F_{} \cos \theta}\) | 4. | \(\dfrac{l \mathrm{~F}_{} \cos \theta}{\mathrm{m}}\) |
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 particle moves in one dimension from rest under the influence of a force that varies with the distance travelled by the particle as shown in the figure. The kinetic energy of the particle after it has travelled \(3~\text{m}\) is:
1. \(2.5~\text{J}\)
2. \(6.5~\text{J}\)
3. \(4~\text{J}\)
4. \(5~\text{J}\)
Statement I: | The magnitude of the momentum of a body is directly proportional to its kinetic energy. |
Statement II: | Kinetic energy increases whenever an external force acts on a moving body. |
1. | Statement I is incorrect and Statement II is correct. |
2. | Both Statement I and Statement II are correct. |
3. | Both Statement I and Statement II are incorrect. |
4. | Statement I is correct and Statement II is incorrect. |
A \(2\) kg particle moves along \(x\)-axis such that its position \((x)\) varies with time \((t)\) as \(x = 2t^{2}+3. \) During the initial \(5\) s, the work done by all the forces acting on the particle is:
1. \(400\) J
2. \(500\) J
3. \(600\) J
4. \(900\) J
The kinetic energy of a particle continuously increases with time. Then we can conclude that:
(a) | The resultant force on the particle must be parallel to the velocity at all instants. |
(b) | The resultant force on the particle must be at an angle less than \(90^{\circ}\) all the time. |
(c) | Its height above the ground level must continuously decrease. |
(d) | The magnitude of its linear momentum is increasing continuously. |
Choose the correct option:
1. | (a) and (b) | 2. | (b) and (c) |
3. | (b) and (d) | 4. | (c) and (d) |