**What Rotational Inertia is and How it Affects Your Everyday Life **

Have you ever wondered why it's harder to get moving on a cold day than on a warm one? It has to do with rotational inertia- the tendency of an object to resist changes in its rotational motion. The rotational inertia of an object depends on its mass and shape. A more massive object has more rotational inertia, and a more compact object has less.

On a cold day, your muscles are stiffer and have less rotational inertia than they do on a warm day. That's why it's harder to get moving. But once you're moving, it's easier to keep going. That's because rotational inertia also depends on the rotational speed of an object.

So, when you're trying to get moving on a cold day, you have to overcome both the stiffness of your muscles and their low rotational inertia. But once you're moving, your muscles have more rotational inertia and can keep you going.

#### Wrapping Up

That's rotational inertia in a nutshell. It's a simple concept, but it has a big impact on your everyday life. The next time you're struggling to get out of bed on a cold morning, remember rotational inertia and give yourself a little extra push.

Following are some of the multiple choice questions on the **Rotational Inertia** with answers that will help the students in developing their knowledge.

## Rotational Inertia MCQ

### 1. What is the angular speed about the rotational axis of the Earth for a person standing on the surface?

### 2. Which is the wrong relation from the following?

### 3. The easiest way to open a heavy door is by applying the force

### 4. The unit of angular velocity is

### 5. Molecules which are having _______ are microwave active.

### 6. 2600 rev/min is equivalent to which of the following?

### 7. Suppose you are designing an engineless car for a downhill coasting race. What type of wheels would be the best?

### 8. Three homogeneous ridged bodies -- a solid shere, a solid cylinder, and a hollow cylinder -- are placed at the top of an incline. If all are released from rest at the same elevation and rolls without slipping, which reaches the bottom first?

### 9. A merry-go-round spins freely when Diego moves quickly to the center along a radius of the merry-go-round. As he does this, it is true to say that

### 10. A uniform solid cylinder with a radius of 10 cm and a mass of 3.0 kg is rotating about its center with an angular speed of 33.4 rpm. What is its kinetic energy?

### 11. The drive chain in a bicycle is applying a torque of 0.850 N ∙ m to the wheel of the bicycle. You can treat the wheel as a thin uniform hoop (or ring) with a mass of 0.750 kg and a radius of 33.0 cm. What is the angular acceleration of the wheel?

### 12. Is torque independent of the location of the origin?

### 13. The rotational inertia of an object is greater when most of the mass is located

### 14. Which object listed below has the greatest momentum?

### 15. What would happen to the length of one day if Earth's moment of inertia were to increase?

### 16. What is Newton's 3rd Law?

### 17. A push or a pull is called a

### 18. Which would have the LEAST gravitational potential energy (GPE)?

### 19. A bowling ball has a mass of 7.00 kg, a moment of inertia of 0.056 kg·m2, and a radius of 0.100 m. If it rolls down the lane without slipping at an angular speed of 4.00 rad/s, what is its rotational kinetic energy?

### 20. Which equation defines rotational kinetic energy?

### 21. A 15-kg child is sitting on a playground teeter-totter, 1.5 m from the pivot. What is the magnitude of the minimum force, applied 0.30 m on the other side of the pivot, that is needed to make the child lift off the ground?

### 22. What is the angular acceleration of an object that has rotational inertia of 4 kg.m2 and submitted to a torque of 8 N.m?

### 23. The object with more rotational inertia needs more torque to move than object with lower inertia?

### 24. If the same torque is applied on a hoop (I=MR2) and a solid disk (I=1/2MR2), after 5s which object will be moving faster?

### 25. The value of torque depends on the rotation axis and the _______________________

### 26. Torque can be positive or negative.

### 27. From the rotational microwave spectrum of 1H35Cl, we find that B = 10.59342 cm-1 . Given that the masses of 1H and 35 Cl are 1.0078250 and 34.9688527 amu, respectively, determine the bond length of the 1H35Cl molecule

### 28. __________ (ω)– the rate at which a body rotates about an axis (radians per second)

### 29. The microwave active molecules are

### 30. Conditions for equilibrium are:1st condition: net force = 02nd condition:net torque = 0

### 31. Calculate the moment of inertia, I, of the molecule 1H35Cl. The masses of the two atoms are mH = 1.673 x 1027 kg and mCl = 5.807 x 1026 kg. The equilibrium bond length of the molecule is 1.275 Å.

### 32. Which of the following molecule has no rotational spectrum?

### 33. The photon described in Question 3 lies within which part of the electromagnetic spectrum?

### 34. The energy in joules of a photon of wavelength 355 nm is

### 35. A photon of wave number 100 cm-1 has a wavelength of

### 36. The different types of energies associated with a molecule are __________

### 37. Moment of inertia depends on

### 38. A body of M.I. 3 kg m² rotating with an angular velocity 2 rad/s has the same K.E. as a mass of 12 kg moving with a velocity of

### 39. The product of the force times the lever arm; the movement of the force about the axis is:

### 40. The dimensions of angular momentum are

### 41. The M.I. of a body does not depends upon

### 42. A body with a definite shape that doesn't change is:

### 43. A dancer on ice spins faster when she folds here arms. This is due to

### 44. Two circular discs A and B have equal masses and uniform thickness but have densities ρ1 and ρ2 such that ρ1 >ρ2. their moment of inertia is

### 45. Centripetal acceleration is directed

### 46. The relation between linear velocity and angular velocity

### 47. A Ferris wheel starts at rest and builds up to a final angular speed of 0.70 rad/s while rotating through an angular displacement of 4.9 rad. What is its average angular acceleration?

### 48. A 0.12-m-radius grinding wheel takes 5.5 s to speed up from 2.0 rad/s to 11.0 rad/s. What is the wheel's average angular acceleration?

### 49. Which of the following is the unit for centripetal force?

### 50. Centripetal acceleration is ...

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