A man standing on a road has to hold his umbrella at 30° with the vertical to keep the rain away. He throws the umbrella and starts running at `10 kmh ^(-1)`.
He finds that raindrops are hitting his head vertically. The actual speed of raindrops is
Options:
(a) `20 kmh^(-1)`
(b) `10sqrt3 kmh^(-1)`
(c) `20sqrt3 kmh^(-1)`
(d) `10 kmh^(-1)`