# Homework Help: Scalar and Vector HELP

1. Sep 25, 2011

### IdleTorque

Scalar and Vector HELP plz

A boat is travelling on a bearing of 25 degrees east of north at a speed of 5 knots ( a knot is 1.852km/hr). After travelling for 3 hours, the boat heading is changed to 180 degrees and it travels for a further 2 hours at 5 knots. What is the boat's bearing from its original position?

Someone help me.

2. Sep 25, 2011

### lewando

Re: Scalar and Vector HELP plz

Welcome to PF. If you missed reading the rules go and do so. Basically, you have to attempt a problem and show what it is that is giving you trouble. For a problem like this, it is a good idea to draw a diagram that represents the facts of the stated problem. From there, explain what is giving you fits.

3. Sep 25, 2011

### IdleTorque

Re: Scalar and Vector HELP plz

oh I'm new here and also new to physics..

I've drawn the diagram but Idk what scales to use cause how they using Knots and time in hours, and they also stating the conversion from knots to km/hr. I've tried alot of assumptions but I just don't seem to get a right answer.

4. Sep 25, 2011

### lewando

Re: Scalar and Vector HELP plz

Since the answer is looking for a bearing, it does not matter if your displacement is in nautical miles or kilometers [EDIT: as long as you pick one and stay consistent with your choice] . the resulting angle will be the same. Nautical miles = knots * hours. What numbers are you getting and how are you getting them?

Last edited: Sep 25, 2011
5. Sep 25, 2011

### IdleTorque

Re: Scalar and Vector HELP plz

so use time as my scale representation? This should solve my question?

6. Sep 25, 2011

### lewando

Re: Scalar and Vector HELP plz

Your vector diagram should show 2 displacement vectors (please show if you can) which should be on a coordinate system with units (scale representation) of nautical miles OR km.

7. Sep 25, 2011

### lewando

Re: Scalar and Vector HELP plz

I stand corrected. Since the speed of the boat is constant, you could use time as your units on your diagram.

8. Sep 25, 2011

### IdleTorque

Re: Scalar and Vector HELP plz

oho thanks for clearing it up for me. I got a reasonable answer which I believe is correct

A bearing of 60 degrees East of North.

Thank you oh great one.. Thank you very much