An observer is positioned at the finishing line of a $100\,\text{m}$ race and wants to measure the winner’s time. He begins his stop-watch when he notices the smoke from the starter’s gun, rather than when he hears the bang. What is the reason for doing this?
- ALight travels much faster than sound.
- BThere is a risk he might respond to an echo from a wall.
- CHumans react slower to sound than to light.
- DHumans react more quickly to sound than to light.