If the length of a simple pendulum is decreased by 2%, find the percentage decrease in its period T, where 
.
The formula for time period -
∴ 
Here 2,π,g have no dimensions. So we can eliminate them.
Now 
By representing in percentage error
⇒ 
⇒ 
⇒ 
⇒ 
Hence the time period becomes 1 %.
1