A container ship is traveling westward at a speed of 5.00 $\mathrm{m} / \mathrm{s} .$ The waves on the surface of the ocean have a wave-length of 40.0 $\mathrm{m}$ and are traveling eastward at a speed of 16.5 $\mathrm{m} / \mathrm{s} .$ (a) At what time intervals does the ship encounter
the crest of a wave? (b) At what time intervals will the ship encounter wave crests if it turns around and heads eastward?