Finding Speed and Direction of Relative Motion on a Moving Ship

[undrcvrbro]

Homework Statement

A child walks due east on the deck of a ship at 1 miles per hour.
The ship is moving north at a speed of 4 miles per hour.

Find the speed and direction of the child relative to the surface of the water.

Homework Equations

The Attempt at a Solution

I've already found the magnitude. But now I can't find the direction.

They want:

"The angle of the direction from the north = "

What does that mean? I've solved it using the inverse tangent for both angles of the triangle and apparently neither is right. So maybe it's even simpler than I think?

 

[Mark44]

Homework Statement

A child walks due east on the deck of a ship at 1 miles per hour.
The ship is moving north at a speed of 4 miles per hour.

Find the speed and direction of the child relative to the surface of the water.

Homework Equations

The Attempt at a Solution

I've already found the magnitude. But now I can't find the direction.

They want:

"The angle of the direction from the north = "

What does that mean? I've solved it using the inverse tangent for both angles of the triangle and apparently neither is right. So maybe it's even simpler than I think?

What did you get for the angle relative to north? It should be somewhere between 10 and 20 degrees east of north.

 

[undrcvrbro]

What did you get for the angle relative to north? It should be somewhere between 10 and 20 degrees east of north.

I got 14.03624347...in radians .2449786631(exact enough for you?)...does that sound about right?

 

[Mark44]

I got 14.03624347...in radians .2449786631(exact enough for you?)...does that sound about right?

Your first value agrees with mine. I didn't calculate it in radians.

 

[undrcvrbro]

Your first value agrees with mine. I didn't calculate it in radians.

Okay, cool. Thanks Mark, for all the help this morning(it's 2:30 here in Ohio). I can now begin my Materials and Energy Balances homework!