Where should you aim to hit a monkey that drops the instant you fire?
A hunter aims a dart gun directly at a monkey hanging from a branch. The instant the dart leaves the gun, the startled monkey lets go and starts to fall. Assuming the dart would have hit the monkey had it stayed put, and ignoring air resistance, where should the hunter aim?
Reveal the answer
Straight at the monkey, not above it. Gravity pulls the falling dart downward by exactly the same amount it pulls the falling monkey, at every instant, regardless of the dart's speed. So the dart always drops to meet the monkey, no matter how fast it's fired. It's a staple classroom demonstration that horizontal and vertical motion are independent under gravity.