Centre of Mass

IMPORTANT

Centre of Mass: Overview

This Topic covers sub-topics such as Linear Momentum of System of Particles, Direction of Movement of Center of Mass, Centre of Mass and Centre of Mass Frame, Centre of Mass of Symmetrical Bodies and, Conservation of Linear Momentum of System of Particles

Important Questions on Centre of Mass

EASY
IMPORTANT

An object of mass  4kg  and another object of mass  1kg  are moving such that they have equal kinetic energy. The ratio of the magnitudes of their linear momentum is

MEDIUM
IMPORTANT

Two spherical bodies of mass M and 5M and radii R and 2R respectively are released in free space with initial separation between their centres equal to 12R. If they attract each other due to gravitational force only, then the distance covered by the smaller body just before collision is–

HARD
IMPORTANT

In the figure shown a small hole of radius 3 cm is made in a semicircular disc of radius 9 cm а distance 12 cm from the centre C of the disc. The distance (in cm) of centre of mass of this system from point C is :-
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HARD
IMPORTANT

 Two rods each of mass m and length L are placed along Xand Y axis as shown in figure. Coordinates of the centre of mass of the combination is

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HARD
IMPORTANT

Two particles of masses 'm' and '2m' are connected by massless string of length 3 meter and whole system is rotating about their centre of mass with angular speed'ω'. The kinetic energy of system is

MEDIUM
IMPORTANT

Linear mass density of rod of length l is directly proportional to  x3, where x is distance from one end of rod. Centre of mass of rod lies at a distance

MEDIUM
IMPORTANT

Two rods each of mass m and length L are placed along X and Y axis as shown in figure.

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Coordinates of the centre of mass of the combination is 

EASY
IMPORTANT

Two masses 2 kg and 5 kg are placed at points 'A' and 'B' as shown in the figure.

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OA= 2i^+3j^AB= 5i^+8j^

Find the coordinates of the centre of mass.

MEDIUM
IMPORTANT

Find the centre of mass from the origin, if the disc and the square plate have same surface density.

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EASY
IMPORTANT

Figure shows a composite object made of same material shaped as a square plate joined with a semicircular disc. Side length of the square is same as the diameter of the semicircle and the dashed line is the interface between the square and semicircle. The centre of mass for the system:

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MEDIUM
IMPORTANT

From a sphere of radius 1 m, a sphere of radius 0.5 m is removed from the edge. The position of centre of mass of the remaining portion from centre of the sphere is

EASY
IMPORTANT

P is the centre of mass of four point masses A,B,C and D, which are coplanar but not collinear.

MEDIUM
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Both are same material Find COM from C.

HARD
IMPORTANT

A 2×2 square sheet is cut out from a 4×4 square sheet as shown in the figure. Shift in centre of mass will be (take length and breadth in metre)

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EASY
IMPORTANT

Two bodies of 2 kg and 4 kg are moving with velocities 20 m/s and 10 m/s respectively towards each other under mutual gravitational attraction. Find the velocity of their centre of mass in m/s.

EASY
IMPORTANT

In free space, a shell moving with velocity 60 m s-1 along the positive x-axis. When it passes through origin, it explodes into two peices of mass ratio 1:2. After the explosion, the velocity of the centre of mass is :-

HARD
IMPORTANT

A 10 g bullet is fired from a rifle horizontally into a 5kg block of wood suspended by a string and the bullet gets embedded in the block. The impact causes the block to swing to a height of 5cm above its initial level. Calculate the velocity of the bullet.

EASY
IMPORTANT

A uniform circular disc has a radius of 20cm. A circular disc of radius 10cm is cut concentrically from the original disc. The shift in centre of mass is

HARD
IMPORTANT

A bob of mass 200 gram is released from rest when string makes an angle 37° with vertical. Sleeve has mass 50 gram and there is no friction anywhere. Displacement of sleeve when bob reaches to the other extreme position will be:

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MEDIUM
IMPORTANT

Two bodies of mass 1 kg and 2 kg are located at 1,2 and -1,3 respectively. Calculate the coordinates of centre of mass.