Center of Mass

IMPORTANT

Center of Mass: Overview

This Topic covers sub-topics such as Centre of Mass, Centre of Mass of Continuous Bodies, Centre of Mass of Two Particles, Centre of Mass of Symmetrical Bodies and, Centre of Mass of More than Two Particles

Important Questions on Center of Mass

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–

EASY
IMPORTANT

If the resultant of all the external forces acting on a body be zero, the centre of mass of the system

EASY
IMPORTANT

Two bodies of different masses 2 kg and 4 kg are moving with velocities 2 m s-1 and 1 m s-1 towards each other due to mutual gravitational attraction. Then the velocity of the centre of mass is

EASY
IMPORTANT

For a bangle, the centre of mass lie outside the body.

EASY
IMPORTANT

The center of mass of a system of particles does not depend upon force acting on particle.

HARD
IMPORTANT

Two particles A and B initially at rest, move towards each other, under mutual force of attraction. At an instance when the speed of A is v and speed of B is 2v, the centre of mass (CM) remains at rest. This statement is _____. Choose from (True/False).

EASY
IMPORTANT

Centre of mass of rectangular lamina lies on the point of intersection of the _____.

EASY
IMPORTANT

The centre of mass of a body lies always inside the body.

EASY
IMPORTANT

For which of the following does the centre of mass lie outside the body ?

HARD
IMPORTANT

In the figure shown the system is at rest initially. Two persons A and B of masses 40 kg each move with speeds v1 and v2 respectively towards each other on a plank lying on a smooth horizontal surface as shown in the figure. Plank travels a distance of 20 m towards right direction in 5 sec. (Here v1 and v2 are given with respect to the plank). Then:

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(i) v1=10 m s-1, v2=0 m s-1
(ii)v1=15 m s-1, v2=5 m s-1
(iii)v1=20 m s-1, v2=10 m s-1

EASY
IMPORTANT

On a horizontal frictionless frozen lake, a girl (36 kg) and a box (9 kg) are connected to each other by means of a rope. Initially, they are 20 m apart. The girl exerts a horizontal force on the box pulling it towards her. How far has the girl travelled when she meets the box?

HARD
IMPORTANT

Two identical objects each of radii R and masses m1 and m2 are suspended using two strings of equal length L as shown in the figure (R<<L). The angle θ which mass m2 makes with the vertical is approximately

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HARD
IMPORTANT

A wide bottom cylindrical massless plastic container of height 9 cm, has 40 identical coins inside it and is floating on water with 3 cm inside the water. If we start putting more of such coins on its lid, it is observed that after N coins are put, its equilibrium changes from stable to unstable. Equilibrium in floating is stable if the geometric center of the submerged portion is above the center of mass of the object). The value of N is closest to

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MEDIUM
IMPORTANT

The centre of mass of solid hemisphere of radius 8 cm is x from the centre of the flat surface. Then value of x in cm is _________ .

HARD
IMPORTANT

Figure below shows a shampoo bottle in a perfect cylindrical shape

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In a simple experiment, the stability of the bottle filled with different amount of shampoo volume is observed. The bottle is tilted from one side and then released. Let the angle θ depicts the critical angular displacement resulting in the bottle losing its stability and tipping over. Choose the graph correctly depicting the fraction f of shampoo filled (f=l corresponds to completely filled) vs the tipping angle θ.

HARD
IMPORTANT

A wide bottom cylindrical massless plastic container of height 9 cm has 40 identical coins inside it and is floating on water with 3 cm inside the water. If we start putting more of such coins on its lid, it is observed that after N coins are put, its equilibrium changes from stable to unstable. Equilibrium in floating is stable if the geometric center of the submerged portion is above the center of mass of the object). The value of N is closest to

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EASY
IMPORTANT

Give an example to show that the following statement is false. 'Any two forces acting on a body can be combined into single force that would have same effect'.

MEDIUM
IMPORTANT

Two heavenly bodies S1 and S2, not far off from each other are seen to revolve in orbits

HARD
IMPORTANT

From the circular disc of radius 4R two small discs of radius R are cut off. The center of mass of the new structure will be

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EASY
IMPORTANT

Consider a two block system having masses MA=3 kg and MB=2 kg, as shown in the figure. If block A is pushed towards the centre of mass through a distance 200 cm, by what distance should the block B be moved so as to keep the centre of mass at the same position.

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