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This mock test of Centre Of Mass MSQ for Physics helps you for every Physics entrance exam.
This contains 10 Multiple Choice Questions for Physics Centre Of Mass MSQ (mcq) to study with solutions a complete question bank.
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*Multiple options can be correct

QUESTION: 1

When a block is placed on a wedge as shown in the figure, the block starts sliding down and the wedge also start sliding on ground. All surfaces are rough. The centre of mass of (Wedge + block) system will move :

Solution:

Friction force between wedge and block is internal i.e. will not change motion of centre of mass. Friction force on the wedge by ground is external and causes centre of mass to move towards right. Gravitational force (** mg**) on block brings it downward hence centre of mass comes down.

The correct answer is: rightward and downward

*Multiple options can be correct

QUESTION: 2

Assuming potential energy * U* at ground level to be zero.

All objects are made up of same material

** U_{P}** = Potential energy of solid sphere

Solution:

centre of mass of cone is on smallest height.

The correct answers are: * U_{S}* >

*Multiple options can be correct

QUESTION: 3

Two particles ** A** and

Solution:

Since ∴ Momentum of system will remain conserved, equal to zero.

The correct answers are:

*Multiple options can be correct

QUESTION: 4

The diagram shows the velocity-time graph for two masses ** R** and

Solution:

(i) Since, both have positive final velocities, hence, both moved in the same direction after collision.

(ii) at ** t** = 2

(iii) by conservation of linear momentum, we can say that mass of ** R** was greater than mass of

The correct answers are: ** R** and

*Multiple options can be correct

QUESTION: 5

A particle strikes a horizontal smooth floor with a velocity * u* making an angle with the floor and rebounds with velocity

Solution:

In horizontal direction, momentum is conserved :

in vertical direction,

The correct answers are: the impulse delivered by the floor to the body is the ratio of the final kinetic energy to the initial kinetic energy is

*Multiple options can be correct

QUESTION: 6

A bag of mass * M* hangs by a long thread and a bullet (mass

Solution:

Since, * F_{ext}* = 0

Hence, momentum will remain conserved equal to

and final kinetic energy is

The correct answers are: Momentum is ** mv**, KE is

*Multiple options can be correct

QUESTION: 7

A ball of mass ** m** moving with a velocity

Solution:

In an elastic collision

* v_{sep}* =

change in momentum of ball is

= 2* m*(

The correct answers are: The average elastic force acting on the ball is The kinetic energy of the ball increase by 2* mu*(

*Multiple options can be correct

QUESTION: 8

Two blocks of equal mass ** m** are connected by an unstretched spring and the system is kept at rest on a frictionless horizontal surface. A constant force

Solution:

The acceleration of the centre of mass is

The displacement of the centre of mass at time ** t** will be

Therefore initial velocity is either in direction of constant force or opposite to it. Hence the particle will move in straight line and speed may increase or decrease. When ** F** and

Initial velocity is perpendicular to constant force, hence the path will be parabolic with speed of particle increasing. means instantaneous velocity is always perpendicular to force. Hence the speed will remain constant. And also constant. Since the particle moves in one plane, the resulting motion has to be circular. Hence initial velocity is in same direction of constant acceleration, therefore, particle moves in straight line with increasing speed.

The correct answers are: The displacement of the centre of mass at time ** t** is The displacement of the right block, if the extension of the spring is

*Multiple options can be correct

QUESTION: 9

For a two-body system in absence of external forces, the kinetic energy as measured from ground frame is *K*_{0} and from centre of mass frame is ** K_{cm}**. Pick up the correct statement.

Solution:

It can be shown that

where ** M** is the total mass of the system and

Due to internal changes ** K_{cm}** can change but

The correct answers are: The kinetic energy as measured from centre of mass frame is least, Only the portion of energy

*Multiple options can be correct

QUESTION: 10

A smooth sphere ** A** of mass

Solution:

Sphere ** A** moving with velocity

The correct answers are: the direction of motion of ** A** and

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