# IMG_20190221_114835.jpgA pendulum clock (fitted with a small heavy bob that is connected with a metal rod) is 5 seconds fast each day at a temperature of 150C and 10 seconds slow at a temperature of 300 C. The temperature at which it is designed to give correct time is

S safeer



let t is the temperature at which clock show right timing

the change in period of a pendulum when the temperature is changed by $\theta$ is

$\Delta T=\frac{1}{2}\alpha \theta T_0$

$5=\frac{1}{2}\alpha (t-15) T_0$

$5=\frac{1}{2}\alpha (t-15) T_0$

at 30 degree loss is 10

$-10=\frac{1}{2}\alpha (t-30) T_0$

solving t=20C

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