A uniform chain of length \(L\) and mass \(M\) is lying on a smooth table and onethird of its length is hanging vertically down over the edge of the table. If \(g\) is acceleration due to gravity, the work required to pull the hanging part on the table is:
1. \(MgL\)
2. \(MgL/3\)
3. \(MgL/9\)
4. \(MgL/18\)
The work done by a person in carrying a box of mass 10 kg to a vertical height of 10 m is 4900 J. The mass of the person is:
1. 40 kg
2. 60 kg
3. 50 kg
4. 55 kg
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 $\mathrm{m}/{\mathrm{s}}^{2}$)
1. 50 J
2. 100 J
3. 25 J
4. Zero
A particle of mass 'm' is projected at an angle '$\mathrm{\alpha \text{'}}$ with the horizontal, with an initial velocity 'u'. The work done by gravity during the time it reaches its highest point is:
1. ${u}^{2}{\mathrm{sin}}^{2}a$
2. $\frac{m{u}^{2}{\mathrm{cos}}^{2}\alpha}{2}$
3. $\frac{m{u}^{2}{\mathrm{sin}}^{2}\alpha}{2}$
4. $\frac{m{u}^{2}{\mathrm{sin}}^{2}\alpha}{2}$
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 bolt of mass 0.3 kg falls from the ceiling of an elevator moving down at a uniform speed of 7 m/s. It hits the floor of the elevator (length of the elevator = 3 m) and does not rebound. What is the heat produced by the impact?
1. 8.82 J
2. 7.65 J
3. 7.01 J
4. 7.98 J
Select the incorrect statement about potential energy:
1.  A change in potential energy is equal to work done against the internal conservative force.

2.  A change in potential energy is independent of the reference point.

3.  A change in potential energy depends on the reference frame.

4.  The potential energy at a point is not unique. 