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Question Bank No: 2

1. Two particles of masses 4 kg and 8 kg are seperated by a distance of 12 m. If they are moving towards wach other under the influence of a mutual force of attraction, then the two particles will meet each other at a distance of

a)		6 m from 8 kg mass
b)		2 m from 8 kg mass
c)		4 m from 8 kg mass
d)		8 m from 8 kg mass

2. A uniform metal disc of radius R is taken and out of it a disc of diameter R is cut-off from the end. The centre of mass of the remaining part will be

a)		$\frac{R}{4}$ from the centre
b)		$\frac{R}{3}$ from the centre
c)		$\frac{R}{5}$ from the centre
d)		$\frac{R}{6}$ from the centre

3. A circular ring of mass 6 kg and radius a is placed such that its centre lies at the origin. Two particles of masses 2 kg each are placed at the intersecting points of the circle eith +ve x-axis and +ve y-axis. Then the angle made by the position vector of centre of mass of entire system with x-axis is

a)		$45^{0}$
b)		$60^{0}$
c)		$\tan^{- 1} (4 / 5)$
d)		$30^{0}$

4. The position of centre of mass of a system consisting of two particles of masses $m_{1}$ and $m_{2}$ seperated by a distance L apart, from m, will be

a)		$\frac{m_{1} L}{m_{1} + m_{2}}$
b)		$\frac{m_{2} L}{m_{1} + m_{2}}$
c)		$\frac{m_{2} L}{m_{1}}$
d)		$\frac{L}{2}$

5. The position of the centre of mass of a cube of uniform density shall be at

a)		the edge of a cube
b)		the centre of one face
c)		the centre of the intersection of diagonals of one face
d)		the geometric centre of the cube

6. A shell is fried from a common with a velocity of v m/s at an angle $θ$ with the horizontal. If explodes into two pieces of equal masses at the highest point of its path. One of the pieces retraces its path to the cannon. the speed of the other piece immediately after explosion is

a)		$3 vCos θ$
b)		$2 vCos θ$
c)		$\frac{3}{2} Cos θ$
d)		$\frac{\sqrt{3}}{2} Cos θ$