Answer:
8.9 s
Explanation:
First, the killer whale swims at 15 m/s for 8.0 s. The distance is:
15 m/s × 8.0 s = 120 m
Then, the killer whale turns 90° and swims at 15 m/s for t seconds. The distance is:
15 m/s × t s = 15t m
These two distances form the legs of a right triangle. The resultant displacement is the hypotenuse. So using Pythagorean theorem:
(180)² = (120)² + (15t)²
32400 = 14400 + 225t²
18000 = 225t²
t² = 80
t = 8.9
The whale swims for 8.9 seconds after turning.