Question

This one stumped me. A man is walking at the rate of 3 ft/s due west on a boat that is travelling due north at the rate of 15 ft/s. Find the final speed and direction of motion of the man.

Answer 1

There might be something wrong with the question, but I'm not sure. Just tell me guys.

Answer 2

Nope, nothing wrong with the question, give me a minute to explain. :)

Answer 3

Ok. This has something to do with bearings?

Answer 4

Yep, and a bit of trigonometry

Answer 5

To get the final speed I should use pythagorean's theorem right?

Answer 6

That's right, you pretty much got this sorted.

Answer 7

getting the bearing for the direction is what stumped me though.

Answer 8

I got the interior angle by using the tan function but the bearing is supposed to be calculated outside the triangle from the north axis.

Answer 9

Moving North at 15ft/s and West at 3ft/s so the interior angle is measured anti clockwise from the north axis. As you're doing bearings, you probably want it measured clockwise from the north axis (True bearing). As you know there's 360 degrees in a full revolution, subtract your angle from 360 and you should get the angle in true bearing.

Answer 10

I was actually referring to compass bearing but thanks anyway.

Answer 11

that interior angle (theta) should be congruent to the outside angle (the bearing)
so the compass bearing should be N 11.3 (degrees) E.

Can anyone verify this?