JAMB 2004 · UME · Q15

Variation

The length $L$ of a simple pendulum varies directly as the square of its period $T$ . If a pendulum with period 4 s is 64 cm long, find the length of a pendulum whose period is 9 s.

Worked solution (try it first)

$L = kT^2$ .
Put in $T = 4$ , $L = 64$ : $64 = 16k$ , so $k = 4$ .
When $T = 9$ : $L = 4 \times 81 = 324$ cm, option D.

Report a problem with this question