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