A mass of 5 kg is moving along a circular path of radius 1 m. If the mas moves with 300 rev/min, its kinetic energy would be
1. 250
2. 100
3. 5
4. 0
1. | 2. | ||
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 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 not do 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 proton is kept at rest. A positively charged particle is released from rest at a distance d in its field. Consider two experiments; one in which the charged particle is also a proton and in another, a positron. At the same time t, the work done on the two moving charged particles is
1. | same as the same force law is involved in the two experiments. |
2. | less for the case of a position, as the position moves away more rapidly and the force on it weakens. |
3. | more for the case of a position, as the position moves away from a larger distance. |
4. | same as the work done by cha particle on the stationary proton. |
A man squatting on the ground gets straight up and stands. The force of reaction of the ground on the man during the process is
1. | constant and equal to mg in magnitude. |
2. | constant and greater than mg in magnitude. |
3. | variable but always greater than mg. |
4. | at first, greater than mg and later becomes equal to mg. |