Question

If the length of a pendulum is made 9 times and mass of the bob is made 4 times then the value of time period becomes

• A. 3T
• B.
• C. 4T
• D. 2T

Answer 1

The correct option is A

3T

The time period of a simple pendulum $T=2\pi \sqrt{\frac{l}{g}}$. It depends on ℓ and does not depend on mass! On increasing ℓ 9 times the new time period T' becomes 3 times the previous

$T^{\prime }=2\pi \sqrt{\frac{l}{g^{\prime }}}=3\times \sqrt{\frac{l}{g}}=3T$