What is the work done by gravity on block A in 2 seconds after the blocks are released? (Pulley is light)
1. 240 J
2. 200 J
3. 120 J
4. 24 J
A weight 'mg' is suspended from a spring. The energy stored in the spring is U. The elongation in the spring is:
1.
2.
3.
4.
The energy required to accelerate a car from rest to 30 m/s is E. The energy required to accelerate the car from 30 m/s to 60 m/s will be:
1. | E | 2. | 2E |
3. | 3E | 4. | 4E |
The speed of a particle moving in a circular path decreases with time. The instantaneous power due to the force acting on it will be:
1. Positive
2. Negative
3. Zero
4. Maybe positive or negative
A body of mass m moving with speed v collides head-on elastically with another identical body at rest. The percentage loss in kinetic energy of the first body will be:
1. | 0% | 2. | 25% |
3. | 50% | 4. | 100% |
A body is obliquely projected from the horizontal ground. The magnitude of gravity's power delivered during its motion from the ground to the topmost point is:
1. | Constant
|
2. | Increases continuously
|
3. | Decreases continuously
|
4. | May increase or decrease depending on the angle of projection |
In the given figure, a man pulls the mass m with the help of a rope. Work done by the man against gravity when mass is lifted by 0.5 m is: (g = 10 )
1. 50 J
2. 100 J
3. 25 J
4. Zero
A particle is suspended by a light rod of length l. The minimum speed at which the particle should be projected, so that it moves in a vertical circle, is:
1. | \(3 \sqrt{g l} \) | 2. | \(\sqrt{2 g l} \) |
3. | \(2 \sqrt{g l} \) | 4. | \(\sqrt{5 g l}\) |
According to the work-energy theorem, the change in kinetic energy of a body is equal to work done by:
1. Non-conservative force on the particle
2. Conservative force on the particle
3. External force on the particle
4. All the forces on the particle
A block is carried slowly up an inclined plane. If is work done by the friction, is work done by the reaction force, is work done by the gravitational force and is the work done by an external force, then choose the correct relation(s):
1.
2. = 0
3.
4. All of these