**Centre Of Mass Quiz and Answers** will be useful for various entrance exam like NEET, AIIMS, JEE. It includes an extensive section of physics and chemistry. These chapter covers each and every topic of System of Particles and Rotational Motion and more. It also contains chapter-wise MCQs with hints and options to make your preparation easy. We also published * System Of Particles And Rotational Motion MCQs and Answers* which are most important and relevant topic to your upcoming examination.

## Centre of Mass Quiz

**1. Masses 1 kg, 1.5 kg, 2 kg, and “M” kg are situated at (2,1,1), (1,2,1), (2,-2,1) and (-1,4,3). What is the value of “M” if their centre of mass is at (1,1,3/2)?**

a) 1 kg

b) 1.5 kg

c) 2 kg

d) 2.5 kg

**Answer: **b

**2.Particles of masses 1 kg and 3 kg are at (2i+5j+13k) m and (-6i+4j-2k) m. What is the position of their centre of mass?**

a) 1/4 (-16i + 17j + 7k) m

b) 1/4 (-8i + 17j + 7k) m

c) 1/4 (-6i + 17j + 7k) m

d) 1/4 (-6i + 17j + 5k) m

**Answer: **a

**3. ****The distance between the centres of carbon and oxygen in the carbon monoxide molecules is 1.13 x 10**^{-10}** m. The distance of the centre of mass of the molecule relat****ive to the oxygen atom is _____**

^{-10}

a) 0.48 x 10^{-10} m

b) 0.64 x 10^{-10} m

c) 0.56 x 10^{-10} m

d) 0.36 x 10^{-10} m

**Answer: **a

**6. Two particles of masses 2 kg and 3 kg are at rest and are separated by 10 m. If they move towards each other under the mutual force of attraction, they would meet at _____**

a) 6 m from 4 kg body

b) 6 m from 6 kg body

c) 4 m from 4 kg body

d) 5 m from 6 kg body

**Answer: **a

**7. A ball of mass 3 kg and a ball of mass 2 kg roll towards each other on a flat surface. How far is the centre of mass from the 3 kg ball of the 2 balls are separated by 6 m?**

a) 1.2 m

b) 2.4 m

c) 3.6 m

d) 4.8 m

**Answer: **b

**8. A uniform disc of radius R is put over another uniform disc of radius 2R of same thickness and density. The edges of the two discs touch each other. What is the position of their centre of mass?**

a) at 5R/3 from the centre of the larger disc

b) at 2R/3 from the centre of the larger disc

c) at 3R/5 from the centre of the larger disc

d) at 2R/5 from the centre of the larger disc

**Answer: **c

**9. Three identical spheres each of radius R are placed such that their centres lie on a straight line. What is the location of their centre of mass from the centre of the first sphere?**

a) R

b) 2R

c) 3R

d) 4R

**Answer: **b

**10. Centre of mass can vary upon the application of internal force.**

a) True

b) False

**Answer: **b

**11. The centre of masses of two particles with masses 2 kg and 1 kg located at (1,0,1) and (2,2,0) is located at _____**

a) 4/3, 2/3, 2/3

b) 2/3, 4/3, 2/3

c) 2/3, 2/3, 4/3

d) 1/3, 2/3, 2/3

**Answer: **a

**12. Two bodies of masses 5kg and 15kg are located in the cartesian plane at (1,0) and (0,1). What is the location of their centre of mass?**

a) 1/4, 1/4

b) 3/4, 3/4

c) 3/4, 1/4

d) 1/4, 3/4

**Answer: **d

**13. The coordinates of the centre of mass of objects of mass 10, 20, 30 kg are (1,1,1) m. Where should an object of mass 40 kg be placed such that the centre of mass of this new system lies at (0,0,0)?**

a) 3/2, 3/2, 3/2

b) -3/2, -3/2, -3/2

c) 3/4, 3/4, 3/4

d) -3/4, -3/4, -3/4

**Answer: **b

**14. The centre of mass for an object always lies inside the object.**

a) True

b) False

**Answer: **b

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

a) Pen

b) Dice

c) Rectangular tile

d) Bangle

**Answer: **d

**16. Numerous particles in a system are placed at a distance of “D” from the origin. The position of the centre of mass will definitely be _____**

a) Equal to D

b) Lesser than or equal to D

c) Greater than D

d) Greater than or equal to D

**Answer: **b

**17. An asteroid enters the atmosphere of the earth and breaks into two pieces. One of the pieces is larger than the other. Which of the following is true considering the centre of mass of both the pieces together?**

a) The centre of mass shifts horizontally towards the larger piece

b) The centre of mass shifts horizontally towards the smaller piece

c) The centre of mass remains in the same trajectory as before breaking apart of the asteroid

d) Depends on the velocity of the asteroid

**Answer: **c

**18. Consider a system on which there are external forces acting. If the vector sum of all these external forces is zero, then the centre of mass _____**

a) must not move

b) may move

c) may accelerate

d) must accelerate

**Answer: **b

**19. For an object with the centre of mass at the origin, the x-coordinates of particles of the object _____**

a) may be all positive

b) may be all negative

c) may be all non-negative

d) cannot be predicted

**Answer: **c

**20. Two bodies of masses 5 kg and 3 kg are moving towards each other at velocities of 3 m/s and 5 m/s, respectively. What is the velocity of their centre of mass?**

a) 0.25 m/s towards 3 kg

b) Upredictable

c) The centre of mass is stationary

d) 0.5 m/s towards 5 kg

**Answer: **c

**21. The velocities of three particles of masses 10 kg, 20 kg and 30 kg are 10i, 10j and 10k m/s, respectively. What is the velocity of their centre of mass?**

a) (i + 2j + 3k) m/s

b) 10 (i + j + k) m/s

c) (10i + 20j + 30k) m/s

d) (3i + 2j + k) m/s

**Answer: **a

**22. A system consists of 2 particles of the same mass. Let one particle be at rest and another particle have an acceleration of “2a”. What would be the acceleration of the centre of mass of the system?**

a) a/4

b) a/2

c) a

d) 2a

**Answer: **c

**23. Two particles A and B, initially at rest, start moving towards each other under a mutual force of attraction. When the speed of A is “10 m/s” and the speed of B is “800 m/s”, what is the speed of their centre of mass?**

a) 0

b) 0.8v

c) 80v

d) 8v

**Answer: **a

**24. A uniform free rectangular steel plate is heated from 273 to 373 kelvin. The initial area of the plate is 15 sq. cm. What is the shift of the centre of mass?**

a)0 cm

b) 1 cm

c) 2 cm

d) 3 cm

**Answer: **a

**25. The centre of mass of the body always lies on the line of symmetry for an object with uniform density.**

a) True

b) False

**Answer: **a