2024 System of Particles and Rotational MotionMoment of Inertia of a Rod Easy Question 9 of 100 in System of Particles and Rotational Motion

The moment of inertia of a thin rod about an axis passing through its mid point and perpendicular to the rod, is 2400 g cm$^2$. The length of the 400 g rod is nearly:

A 20.7 cm
B 72.0 cm
C 8.5 cm
D 17.5 cm

The answer is C.

Solution

Moment of inertia of a thin rod about an axis through its mid-point, perpendicular to the rod: $I = \frac{ML^2}{12}$ $\frac{400 \times L^2}{12} = 2400$ $L^2 = \frac{12 \times 2400}{400} = 72$ $L = \sqrt{72} \approx 8.5$ cm

Concept Moment of inertia of thin rod about perpendicular bisector

System of Particles and Rotational Motion in past papers

100 questions from this chapter have appeared across 27 exam years.