# 50+ Centre of Mass Quiz and Answers

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

a) 1 kg

b) 1.5 kg

c) 2 kg

d) 2.5 kg

#### 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

#### 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 relative to the oxygen atom is _____

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

#### 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

a) 1.2 m

b) 2.4 m

c) 3.6 m

d) 4.8 m

#### 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

a) R

b) 2R

c) 3R

d) 4R

a) True

b) False

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

a) 1/4, 1/4

b) 3/4, 3/4

c) 3/4, 1/4

d) 1/4, 3/4

#### 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

a) True

b) False

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

a) Pen

b) Dice

c) Rectangular tile

d) Bangle

#### 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

#### 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

#### 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

#### 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

#### 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

#### 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

a) a/4

b) a/2

c) a

d) 2a

a) 0

b) 0.8v

c) 80v

d) 8v

a)0 cm

b) 1 cm

c) 2 cm

d) 3 cm