Conservative Forces and Potential Energy

Q. An ejector mechanism consists of a helical compression spring having a spring constant of $K=981\times {10}^3\frac{N}{m}$. It is pre-compressed by 100 mm from its free state. If it is used to eject a mass of 100 kg held on it, the mass will move up through a distance of

1. 100
2. 5000 mm
3. 581 mm
4. 1000 mm

Q. A block of mass of 5 kg is released from rest from a position A on an inclined plane as shown on the figure. If the coefficient of the friction between the block and the plane is 0.2, the velocity at which it will touch the ground at B is $(g=10m/s^2)$

1. 10 m/s
2. 15 m/s
3. 20 m/s
4. 24 m/s

Q. A body A of weight 10 kg with C.G 25 cm from the axis of roation is to be balanced by another body B of weight 5 kg. The radius at which the C.G of weight B should be placed is

1. 2 cm
2. 12.5 cm
3. 50 cm
4. None of these

Q. A uniform chain of mass m and length l overhangs a table with its two third parts on the table. The minimum work to be done by a person to put the hanging part back on the table is

1. $\frac{mgl}{18}$
2. $\frac{mgl}{6}$
3. $\frac{mgl}{9}$
4. $\frac{mgl}{3}$