Question

A speedboat moves west at 108 km/h for 22.0 min. It then moves at 60.0° south of west at 90.0 km/h for 10.0 min.

What is the average speed for the trip?


What is the magnitude of average velocity for the trip?


What is the direction of average velocity for the trip? Enter the angle in degrees where negative indicates north of west and positive indicates south of west.

Answer 1

108 km/hr = 1.8 km/min

90 km/hr = 1.5 km/min

V1 = (-39.6, 0)

V2 = (-10.6, -10.6) (10.6^2 + 10.6^2)^1/2 = 15 1.5 km/min * 10 min

V = (-50.2, -10.6) final displacement vector

Total time = 22 + 10 = 32 min

S = (50.2^2 + 10.6^2)^1/2 = 51.3 km

Average speed = (1.8 * 22 + 1.5 * 10) / 32 = 1.71 km / min

Displacement = 51.3 km

Average velocity = 51.3 / 32 = 1.60 km/min

Direction = 10.6 / 50.2 = .211 or 11.9 deg S of W