Question

A wall clock uses a simple pendulum, it is accurate at earth surface. If it is taken to high altitude

• A. it will run fast
• B. its length should be increased to keep it accurate
• C. its length should be decreased to keep it accurate.
• D. Even if length is changed it cannot be accurate.

Answer 1

The correct option is C its length should be decreased to keep it accurate.

Time period of a simple pendulum is

$T=2\pi \sqrt{\frac{L}{g}}$

As altitude increases $g$ decreases

So as to keep it accurate $L$ should also be decreased