A pendulum bob is pulled up until it is 20 cm above its lowest point, then released. Estimate its speed at the bottom of the swing.

2 (answers within ±0.3 count)

$v = \sqrt{2 \times 9.8 \times 0.2} \approx 1.98$ m/s. Notice the string tension does no work, it always pulls perpendicular to the motion, so only gravity matters.