Correct option is B
When children hold a larger bat closer to its center, they reduce the radius of gyration, making it easier to swing. The radius of gyration is a measure of the distribution of mass around an axis of rotation.
Key Points: 1. Radius of Gyration (k):
· Defined as the root mean square distance of an object's mass from its axis of rotation.
· A shorter radius of gyration reduces the moment of inertia, making the object easier to rotate.
2. Moment of Inertia (I):
· Given by I=mk2I = mk^2I=mk2, where mmm is the mass and kkk is the radius of gyration.
· Reducing kkk (by holding the bat closer to the center) decreases III, requiring less torque to swing the bat.
Why the Other Options Are Incorrect: · (a) The center of mass is reduced: The center of mass doesn't change significantly because the bat's mass distribution remains the same.
· (c) The effective mass is increased: The effective mass does not increase. In fact, the swing feels lighter due to reduced rotational resistance.
· (d) The radius of gyration is increased: Holding the bat closer to the center reduces, not increases, the radius of gyration.
Correct Answer:
(b) The radius of gyration is reduced
Information Booster 1. Practical Application:
· This principle applies to sports like cricket, baseball, and golf, where controlling the bat or club is essential for performance.
· Beginners often "choke up" on the bat to reduce the effort needed for swinging.
2. Biomechanics of Swinging:
· A reduced radius of gyration leads to faster swings with less energy expenditure.
· Professional athletes may prefer longer grips for increased power once they master control.
3. Physics Insight:
· Torque (τ\tauτ) required to rotate an object is proportional to its moment of inertia (III).