A small disc of radius 2 cm is cut from a disc of radius 6 cm. If the distance between their centres is 3.2 cm, what is the shift in the centre of mass of the disc?

0.4 cm

2.4 cm

1.8 cm

1.2 cm

Solution

0.4 cm

The situation can be shown as: Let radius of complete disc is a and that of small disc is b. Also let centre of mass now shifts to 0₂ at a distance X₂ from original centre

The position of new centre of mass is given by

$X_{CM} = \frac{- σ . {πb}^{2} . x_{1}}{σ . π a^{2} - σ . π b^{2}}$

Here, a = 6 cm, b = 2 cm, x₁ = 3.2 cm

$∴ X_{CM} = \frac{- σ \times π {(2)}^{2} \times 3.2}{σ \times π \times {(6)}^{2} - σ \times π \times {(2)}^{2}} = \frac{12.8}{32 π}$

⇒ X_CM = 0.4 cm

Some More Questions From Motion in Straight Line Chapter

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Motion In Straight Line

A small disc of radius 2 cm is cut from a disc of radius 6 cm. If the distance between their centres is 3.2 cm, what is the shift in the centre of mass of the disc?

0.4 cm

2.4 cm

1.8 cm

1.2 cm

Some More Questions From Motion in Straight Line Chapter

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What is the most essential thing to study the motion of a body?

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For Daily Free Study Material Join wiredfaculty

Motion In Straight Line

A small disc of radius 2 cm is cut from a disc of radius 6 cm. If the distance between their centres is 3.2 cm, what is the shift in the centre of mass of the disc? 0.4 cm 2.4 cm 1.8 cm 1.2 cm

Some More Questions From Motion in Straight Line Chapter

What is motion?

Is absolute rest or absolute motion possible?

What is the most essential thing to study the motion of a body?

Can a body be always at rest in some frame?

Can a body be in motion in the frame associated with the body itself?

When an object in motion can be considered as particle or point object?

Can you think of physical phenomena involving the moon in which moon cannot be treated as particle?

A train is crossing the bridge. Can it be taken as a particle?

Can a train be taken a particle? Give an example in support of your answer.

A particle is moving along curved line in space. Is the motion one dimensional?

Mock Test Series

NCERT Sample Papers

Entrance Exams Preparation

A small disc of radius 2 cm is cut from a disc of radius 6 cm. If the distance between their centres is 3.2 cm, what is the shift in the centre of mass of the disc?

0.4 cm

2.4 cm

1.8 cm

1.2 cm