JEE Exam  >  JEE Tests  >  Test: Centre Of Mass (Competition Level) - JEE MCQ

Test: Centre Of Mass (Competition Level) - JEE MCQ


Test Description

30 Questions MCQ Test - Test: Centre Of Mass (Competition Level)

Test: Centre Of Mass (Competition Level) for JEE 2025 is part of JEE preparation. The Test: Centre Of Mass (Competition Level) questions and answers have been prepared according to the JEE exam syllabus.The Test: Centre Of Mass (Competition Level) MCQs are made for JEE 2025 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for Test: Centre Of Mass (Competition Level) below.
Solutions of Test: Centre Of Mass (Competition Level) questions in English are available as part of our course for JEE & Test: Centre Of Mass (Competition Level) solutions in Hindi for JEE course. Download more important topics, notes, lectures and mock test series for JEE Exam by signing up for free. Attempt Test: Centre Of Mass (Competition Level) | 30 questions in 60 minutes | Mock test for JEE preparation | Free important questions MCQ to study for JEE Exam | Download free PDF with solutions
Test: Centre Of Mass (Competition Level) - Question 1

A square plate and a circular plate made up of same material are placed touching each other on a horizontal table. If the side length of square plate is equal to diameter of the circular plate, then the centre of mass of the combination will be  

Detailed Solution for Test: Centre Of Mass (Competition Level) - Question 1
Let m be the mass per unit area.

Test: Centre Of Mass (Competition Level) - Question 2

A rigid body consists of a 3 kg mass located at   and a 2 kg mass located at  .The position of center of mass is  

Detailed Solution for Test: Centre Of Mass (Competition Level) - Question 2

The coordinates of the center of mass (CM) for a system of particles is given by the formula:

The x-coordinate of the center of mass can be calculated as:

Substituting the values:
 m= 3 kg, x1= 2m
 m2 = 2 kg, x2= 4 m

The y-coordinate of the center of mass can be calculated as:

Test: Centre Of Mass (Competition Level) - Question 3

A dog weighing 5 kg is standing on a flat boat so that it is 10 meters from the shore. It walks 4 m on the boat towards the shore and then halts. The boat weighs 20 kg and one can assume that there is no friction between it and water. The dog from the shore at the end of this time is  

Detailed Solution for Test: Centre Of Mass (Competition Level) - Question 3

Test: Centre Of Mass (Competition Level) - Question 4

Particles of masses 1 kg and 3 kg are at m  then instantaneous position of their centre of mass is  

Detailed Solution for Test: Centre Of Mass (Competition Level) - Question 4

xcom=m1x1+m2x2/m1+m2
=1x2+3x (-6)
=-4î
vcom= m1y1+m2y2/m1+m2
=1x5+3x4/4
=17/4 ĵ
zcom= m1z1+m2z2/m1+m2
=13-6/4
=7/4 k̂
rcom=-4î+17/4 ĵ+7/4 k̂
=1/4(-16î+17ĵ+7k̂)m

Test: Centre Of Mass (Competition Level) - Question 5

A uniform metre rod is bent into L shape with the bent arms at 90o to each other. The distance of the centre of mass from the bent point is  

Detailed Solution for Test: Centre Of Mass (Competition Level) - Question 5

Test: Centre Of Mass (Competition Level) - Question 6

A thin uniform rod of length L is bent at its mid point as shown in the figure. The distance of the centre of mass from the point O is  

Detailed Solution for Test: Centre Of Mass (Competition Level) - Question 6


 

Test: Centre Of Mass (Competition Level) - Question 7

Two identical thin uniform rods of length L each are joined to form T shape as shown in the figure. The distance of centre of mass from D is  

Detailed Solution for Test: Centre Of Mass (Competition Level) - Question 7


On solving we get 3L/4
 

Test: Centre Of Mass (Competition Level) - Question 8

Two particles of equal masses have velocities    First particle has an acceleration    while the acceleration of the other particle is zero. The centre of mass of the two particles moves in a path of  

Detailed Solution for Test: Centre Of Mass (Competition Level) - Question 8



Test: Centre Of Mass (Competition Level) - Question 9

Two bodies of masses m1 and m2 are moving with velocity v1 and v2 respectively in the same direction. The total momentum of the system in the frame of reference attached the centre of mass is (v is relative velocity between the masses) 

Detailed Solution for Test: Centre Of Mass (Competition Level) - Question 9

P = m1(v1 - vc) + m2(v2 – vc)
P = m1v1 + m2v2 – (m1 + m2)vc
Also, we know that vc = m1v1 + m2v2/(m1 + m2)
Hence P = 0

Test: Centre Of Mass (Competition Level) - Question 10

A body of mass m moving at a constant velocity v hits another body of the same mass moving with a velocity v/2 but in the opposite direction and sticks to it. The common velocity after collision is 

Detailed Solution for Test: Centre Of Mass (Competition Level) - Question 10


Hence v = v/4
 

Test: Centre Of Mass (Competition Level) - Question 11

A body of mass 5 kg is acted on by a net force F which varies with time t as shown in graph, then the net momentum in SI units gained by the body at the end of 10 seconds is

 

Detailed Solution for Test: Centre Of Mass (Competition Level) - Question 11

Area under F-t curve = change in momentum.

Test: Centre Of Mass (Competition Level) - Question 12

A force time graph for the motion of a body is as shown in figure. Change in linear momentum between 0 and 6 s is 

Detailed Solution for Test: Centre Of Mass (Competition Level) - Question 12

Area under F-t curve = change in momentum = 2 x (-2) + 1 x 4 = -4 + 4 = 0  

Test: Centre Of Mass (Competition Level) - Question 13

A ball of mass 10 g hits a hard surface vertically with a speed of 5 m/s and rebounds with the same speed. The ball remains in contact with the surface for 0.01 s. The average force exerted by the surface on the ball is  

Detailed Solution for Test: Centre Of Mass (Competition Level) - Question 13

Average force = change in momentum/time
Change in momentum = m(v1 - v2)
=0.01[ 5 - (-5)]
=0.1
Average force = 0.1/0.01
= 10 N

Test: Centre Of Mass (Competition Level) - Question 14

Locate the centre of mass of a uniform semicircular ring (or wire) of radius R and linear mass density λ.

Detailed Solution for Test: Centre Of Mass (Competition Level) - Question 14

Let us take the centre of the ring at origin O. Consider a small element of arc length dl of the ring. Let θ be the angle which the radius vector of the element makes with the x-axis as shown in Fig.
Let dθ be the angle subtended by the element at the centre. Then dl=Rdθ. Mass of the element is
dm=λdl=λRdθ
The x and y components of radius vector R are x=Rcosθ and y=Rsinθ. Then

Thus, the centre of mass is at a distance of 2R/π from origin O on the y-axis. By symmetry, the x-coordinate of centre of mass is x=0 (i.e. at O).

Test: Centre Of Mass (Competition Level) - Question 15

The linear momentum of a particle varies with time t as p = a + bt + ct2. Which of the following statement is correct?  

Detailed Solution for Test: Centre Of Mass (Competition Level) - Question 15

Clearly, the force is time-dependent.  

Test: Centre Of Mass (Competition Level) - Question 16

A block Q of mass M is placed on a horizontal frictionless surface AB and a body P of mass m is released on its frictionless slope. As P slides by a length L on this slope of inclination θ, the block Q would slide by a distance

Detailed Solution for Test: Centre Of Mass (Competition Level) - Question 16

Here, the x co-ordinate of centre of mass of the system remains unchanged when the mass m moved a distance Lcosθ, let the mass (m+M) moves a distance x in the backward direction.
∴ (M+m)x−mLcosθ=0

Test: Centre Of Mass (Competition Level) - Question 17

A bomb of mass 12 kg, initially at rest explodes into two pieces of masses 4 kg and 8 kg. The speed of the 8 kg mass is 6 m/s. The kinetic energy of the 4 kg mass is  

Detailed Solution for Test: Centre Of Mass (Competition Level) - Question 17

 

Test: Centre Of Mass (Competition Level) - Question 18

A pulley fixed to the ceiling carries a string with blocks of mass m and 3 m attached to its ends. The masses of string and pulley are negligible. When the system is released, its centre of mass moves with what acceleration?

Detailed Solution for Test: Centre Of Mass (Competition Level) - Question 18

Consider the following diagram,

The acceleration of the whole system can be found by force balance i.e.,

The negative sign shows that the acceleration is downwards.

Test: Centre Of Mass (Competition Level) - Question 19

A 1 kg ball moving at 12 m/s collides head-on with a 2 kg ball moving in the opposite direction at 24 m/s. If the coefficient of restitution is 2/3 then the final speeds of the two balls are respectively  

Detailed Solution for Test: Centre Of Mass (Competition Level) - Question 19

Test: Centre Of Mass (Competition Level) - Question 20

Two spheres A and B of masses m and 2m and radii 2R and R respectively are placed in contact as shown. The COM of the system lies

Detailed Solution for Test: Centre Of Mass (Competition Level) - Question 20

Let O(0,0) be the centre of sphere A then,

= at the point of contact

Test: Centre Of Mass (Competition Level) - Question 21

Ball 1 collides with another identical ball 2 at rest as shown in figure. For what value of coefficient of restitution e, the velocity of second ball becomes two times that of 1 after collision

 

Detailed Solution for Test: Centre Of Mass (Competition Level) - Question 21

From conservation of momentum,   mu = mv1 + mv2                      (1)

 

 

Test: Centre Of Mass (Competition Level) - Question 22

There are some passengers inside a stationary railway compartment. The centre of mass of the compartment itself (without the passengers) is C1, while the centre of mass of the 'compartment plus passengers' system is C2. If the passengers move about inside the compartment then

Detailed Solution for Test: Centre Of Mass (Competition Level) - Question 22

When net Fatermal =0, then the centre of mass of the system remains at rest. Thus if the passenger move about inside the compartment which donot require any external force, so the centre of mass of the "passenger + compartment" system must remain at rest and hence C2 will be fixed w.r.t ground.
Also due to the movement of the passenger, the position of centre of mass of the passengers only will change, thus C1 will have to move in such a way that C2 may remain fixed w.r.t ground.

Test: Centre Of Mass (Competition Level) - Question 23

“A truck of mass 15 tons moving with one meter per second collides with the stationary truck of 10 tons and they start to move together.
In the above question, the energy lost in the collision is”

Detailed Solution for Test: Centre Of Mass (Competition Level) - Question 23

So, m1v1 = (m1 + m2)v
Hence v = 0.6 m/s
Now, loss in KE = KE initial – KE final = 7500 – 4500 = 3000 J

Test: Centre Of Mass (Competition Level) - Question 24

Three masses are placed on the x -axis :300 g at origin, 500 g at x=40 cm and 400 g at x=70 cm. The distance of the centre of mass from the origin is

Detailed Solution for Test: Centre Of Mass (Competition Level) - Question 24

Test: Centre Of Mass (Competition Level) - Question 25

A particle of mass 1 g moving with a velocity  m/s experiences a perfectly inelastic collision with another particle of mass 2 g and moving with velocity  m/s. The velocity of the combined particle is  

Detailed Solution for Test: Centre Of Mass (Competition Level) - Question 25

Test: Centre Of Mass (Competition Level) - Question 26

With O as the origin of the coordinate axis, the X and Y-coordinates of the centre of mass of the system of particles shown in the figure may be given as? (Here m and 2m represent the masses of the particles)

Detailed Solution for Test: Centre Of Mass (Competition Level) - Question 26

Test: Centre Of Mass (Competition Level) - Question 27

A batsman deflects a ball at an angle 90o without changing its initial speed which is equal to 54 km/h. The impulse imparted to the ball whose mass is 0.5 kg is  

Detailed Solution for Test: Centre Of Mass (Competition Level) - Question 27

Test: Centre Of Mass (Competition Level) - Question 28

Four particles of masses m1, m2, m3 and m4 are placed at the vertices A,B C and D as respectively of a square shown. The COM of the system will lie at diagonal AC if

Detailed Solution for Test: Centre Of Mass (Competition Level) - Question 28

Possible when m2 = m4

Test: Centre Of Mass (Competition Level) - Question 29

A ball moving with a constant speed hits another identical ball at rest. If co-efficient of restitution equals (2/3) then the ratio of speeds of the second ball to that of the first ball after collision will be  

Detailed Solution for Test: Centre Of Mass (Competition Level) - Question 29

The final velocities in case of one dimensional semi elastic collision are
V1 = {(m1 - em2)/(m1 + m2)}u1 + {(1 + e)/(m1 + m2)}m2u2
V2 = {(m2 - em1)/(m1 + m2)}u2 + {(1 + e)/(m1 + m2)}m1u1
Here, u1 = u and u2 = 0; e = (2/3) and m1 = m2 = m
By substituting these values we get V2: V1 = 5 : 1

Test: Centre Of Mass (Competition Level) - Question 30

The centre of mass of three bodies each of mass 1 kg located at the points (0,0),(3,0) and (0,4) in the XY plane is

Detailed Solution for Test: Centre Of Mass (Competition Level) - Question 30


Therefore the coordinates of centre of mass are (1,4/3).

Therefore the coordinates of centre of mass are (1,4/3)

Information about Test: Centre Of Mass (Competition Level) Page
In this test you can find the Exam questions for Test: Centre Of Mass (Competition Level) solved & explained in the simplest way possible. Besides giving Questions and answers for Test: Centre Of Mass (Competition Level), EduRev gives you an ample number of Online tests for practice
Download as PDF