RRB Technician 2014 Ques 23
Question: If the length of second’s pendulum is decreased by 2%, how many seconds it will lose per day?
Options:
A) 216s
B) 432s
C) 864s
D) 1728s
Show Answer
Answer:
Correct Answer: C
Solution:
- $ T=2\pi \sqrt{\frac{l}{g}},T’=2\pi \sqrt{\frac{98l}{100g}} $ $ \frac{T’}{T}=\sqrt{\frac{98}{100}}={{( 1-\frac{2}{100} )}^{\frac{1}{2}}}=( 1-\frac{1}{100} ) $ by binomial theorem. $ \frac{1}{100}=\frac{T-T’}{T}= $ Change in time per second Change per day = Change in 86400 s $ =\frac{86400\times 1}{100}=864s $
BETA
