# Rotational motion practice problems

This article contains Rotational motion practice problems for class 11. In this article I have given definition and derivation based problems, very short answer type questions , short answer type questions.
You can print this article and practice these problems.
You read notes on this chapter before practicing these questions. For them please visit this link
Center of mass : System of particles and Collision
Other assignments(Included with Linear momentum) for this chapter which you can have a look are
Assignment 1
Assignment 2
Assignment 3
Assignment 4


## Rotational motion practice problems

Q 1. Define center of mass and center of gravity.

Q 2. Make a table showing COM of following regular symmetrical bodies.

1. Thin rod
2. Ring
3. Disc
4. Rectangular lamina
5. Cubical block
6. Cylinder
7. Sphere
8. Triangular lamina
9. Right circular cone

Also draw their respective diagrams pointing out position of COM in respective bodies.

Q 3. Derive three equation of rotational motion under constant angular acceleration from first principle.

Q 4. On what factor does the turning effect of a force depend ? What is the  turning effect of a force called?

Q 5. Define term torque or moment of force . Give its units and dimensions.

Q 6. State and explain the principle of moments of rotational equilibrium.

Q 7. What is a couple? What effect  does it have on a body ? Show that the moment of couple is same irrespective of the point of rotation of a body.

Q 8. In the HCL molecule, the separation between the nuclei of the two atoms is 1.27 A. Calculate the approximate location of the center of mass of the molecule. Given: Chlorine atom is heavier and 35.5 times as massive as a hydrogen atom and nearly all the mass of an atom is concentrated in its nucleus.      (Ans:-  1.235$\AA$)

Q 9. What will be the nature of motion of center of mass of an isolated system .

Q 10. The motor of an engine is rotating about its axes with an angular velocity of 120 r.p.m. It comes to rest in IOS, after being switched off. Assuming constant deceleration, calculate the number of revolutions made by it before coming to rest. (Ans:- 10)

Some other resources you can look for reference are
https://en.wikipedia.org/wiki/Center_of_mass
https://www.khanacademy.org/science/physics/linear-momentum/center-of-mass/a/what-is-center-of-mass
http://hyperphysics.phy-astr.gsu.edu/hbase/cm.html
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