4. [5 marks] At a marathon there is loud music at a water station to cheer the

runners on. The marathon route turns a right-angled corner 200 m past the

water station. The runner’s speed is 4 m/s. How fast is the distance between the runner and the water station increasing when the runner is 100 m past the corner? Include a sentence answer with units.

Help would be appreciated. Thank you.