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Units And Measurement

Question
CBSEENPH11020757
Wired Faculty App

A thin rod of length L and Mass M is bent at its midpoint into two halves so that the angle between them is 90o. The moment of inertia of the bent rod about an axis passing through the bending point and perpendicular to the plane defined by the two halves of the rod is 

  • ML2/24

  • ML2/12

  • ML2/6

  • fraction numerator square root of 2 space ML squared over denominator 24 end fraction

Solution

B.

ML2/12

Since rod is bent at the middle, so each part of it will have same length (L/2) and mass (M/2) as shown,

Moment of inertia of each part through its one end
 equals space 1 third open parentheses straight M over 2 close parentheses open parentheses straight L over 2 close parentheses squared
Hence, net moment of inertia through its middle point O is
straight I space equals space 1 third open parentheses straight M over 2 close parentheses open parentheses straight L over 2 close parentheses squared space plus 1 third open parentheses straight M over 2 close parentheses open parentheses straight L over 2 close parentheses squared equals 1 third open square brackets ML squared over 8 plus ML squared over 8 close square brackets space equals space ML squared over 12

Some More Questions From Units and Measurement Chapter

Can we use different units to measure same physical quantity?

To measure a physical quantity X, the unit U is repeatedly used for n times. What is the magnitude of physical quantity?

Does the numerical factor in the quantitative measurement depend on the system of unit used?

Is one unit sufficient to measure a physical quantity?

Can a physical quantity have two or more units? Give example.

What are fundamental quantities?

How many fundamental quantities are there in mechanics?

How many fundamental quantities are there in Physics?

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