Question

A pendulum clock is 5 sec. Slow at a temperature `30^(@)C` and `10` sec. fast at a temperature of `15^(@)C`, At what temperature does it give the correct time-
A. `18^(@)C`
B. `20^(@)C`
C. `25^(@)C`
D. None of these

Answer 1

Correct Answer - C
Let correct time at `theta^(@)C` & `15^(@) lt theta lt 30^(@)`
apply `Deltat = 1/2 alpha Deltatheta.t`
for slow:
`5 = 1/2 alpha xx (30^(@) - theta).t "….."(1)`
for fast :
`10 = 1/2 alpha xx (theta - 15)t "……"(2)`
By `(1)(2) : theta = 25^(@)C`