## Circular Motion Very Short Answer Type Questions

**Question 1. Name the unit of angular displacement.**

**Answer:** Degree or radian

**Question 2. State true or false—an angle measured in radians is dimensionless.**

**Answer:** True

**Question 3. What kind of vector is angular velocity?**

**Answer:** Axial vector

**Question 4. What is the angular velocity of the second hand of a clock?**

**Answer:** 10.105 rad · s^{-1}

**Question 5. Uniform circular motion is an example of uniform velocity’—state whether the statement is correct.**

**Answer:** No

**Question 6. What do you mean by the term frequency?**

**Answer:** Complete rotation number per second

**Question 7. What is the relation between time period and frequency?**

**Answer:** v = \(\frac{1}{T}\)

**Question 8. What is the dimension of angular acceleration?**

**Answer:** T^{-2}

**Quetsion 9. 1 rps = ______ rpm = _______ rph**

**Answer:** 60, 3600

**Question 10. 1 rpm =? rad · s ^{-1}**

**Answer:**π/30

**Question 11. What is the vector relation of linear acceleration \(\vec{a}\) and angular acceleration (\(\vec{alpha}\))?**

**Answer:** \(\vec{a}\) = \(\vec{alpha}\) x \(\vec{r}\)

**Question 12. In the case of uniform circular motion, the velocity and the acceleration are perpendicular to each other. [State true or false]**

**Answer:** True

**Question 13. What is the angular velocity of the minute hand of a clock in rad •· s ^{-1}? **

**Answer:**π/1800

**Question 14. If the frequency of revolution of a body is n, then what will be the velocity of revolution?**

**Answer:** ω = 2πn

**Question 15. A particle of mass m is moving in a circular path of radius r with a uniform speed v. The centripetal force on the body is \(\frac{m \omega^2}{r}\). When the particle is displaced half of the distance, then what is the work done by the centripetal force?**

**Answer:** Zero

**Question 16. What does supply the necessary centripetal force when a stone tied with a string is rotated along a circular Path?**

**Answer:** Tension in the string

**Question 17. What does provide a planet the necessary centripetal force to revolve around the sun?**

**Answer: The gravitational** force of the sun

**Question 18. If a particle moves in a circular path with constant speed, what should be the direction of its resultant acceleration?**

**Answer:** Towards the centre

**Question 19. In the case of railway tracks, which rail is to be kept at a slightly higher level near a bend?**

**Answer:** Outer rail

**Question 20. The radius of a curved path is r and the coefficient of friction between a car and the path is μ. What is the maximum speed at which the car can turn at a bend without skidding?**

**Answer:** \(V_m=\sqrt{\mu r g}\)

**Question 21. Is it possible for a cyclist to lean through an angle of 45° with the vertical when he takes a turn?**

**Answer:** No

**Question 22. Why is a centripetal force so-called?**

**Answer:** It is centre-seeking

**Question 23. For uniform circular motion, does the direction of the centripetal force depend on the sense of rotation (i.e., clockwise or anti-clockwise)?**

**Answer:** No

**Question 24. A body is moving along a circular path such that its speed always remains constant. Should there be a force acting on the body?**

**Answer:** Yes

**Question 25. What type of acceleration does a body moving along a circular path possess?**

**Answer:** Centripetal

**Question 26. A piece of stone is tied with a thread and is rotated along a horizontal circular path. If the thread snaps suddenly, in which direction will the stone fly?**

**Answer:** Tangentially

**Question 27. What supplies the necessary centripetal force to the electrons in an atom to revolve around the nucleus?**

**Answer:** Electrostatic force of attraction

**Question 28. When a car turns towards the right while moving, the passengers inside the car lean towards _______.**

**Answer:** Left

**Question 29. To avoid an accident of a moving car near a bend, _______ force is supplied by banking the road.**

**Answer:** Centripetal

**Question 30. A cyclist is riding on a cycle with speed v and while negotiating a circular path of radius r, he leans at an angle θ with the ground. Then, what will be the value of tanθ?**

**Answer:** \(\frac{rg}{v^2}\)

**Question 31. The angular momentum of a body of mass m rotating along a circular path of radius r with uniform speed is L. What is the magnitude of the centripetal force acting on it?**

**Answer:** \(\frac{L^2}{mr^3}\)

**Question 32. When a motor car moves speedily on a convex path, how do the passengers inside the car feel?**

**Answer:** Lighter

**Question 33. At which plane on earth, the centripetal force is maximum?**

**Answer:** Equatorial plane

**Question 34. Due to which type of force butter comes out during stirring of milk? **

**Answer:** Centrifugal

**Question 35. A body of mass m is rotated along a circular path of radius r with uniform speed v. Centripetal force acting on the body is \(\frac{m v^2}{r}\). If the body travels through a semicircular path, then what will be the work done by the centripetal force?**

**Answer:** Zero