# Homework Help: Trucks travels beneath an airplane .

1. Oct 15, 2012

### ArcherofScience

trucks travels beneath an airplane.....

1. The problem statement, all variables and given/known data

A truck travels beneath an airplane that is
moving 180 km/h at an angle of 39 to the
ground. How fast must the truck travel to stay be-
neath the airplane? What is the magnitude of the vertical component of the velocity of the plane? Answer in units of km/h

2. Relevant equations

My physics teacher said the question is identifying the horizontal and vertical components. So I had to do Vcostheta and Vsintheta.

3. The attempt at a solution

Vcostheta=180cos39=139.8863 km/h
vsintheta=180sin39=113.2777 km/h

my problem is, I don't understand which direciton the vectors are. Is it going north of east or south of east, or what? I can't identify them in the problem and I can't tell if the answers need a negative sign or positive sign.

2. Oct 15, 2012

### Dick

Re: trucks travels beneath an airplane.....

The problem is only asking you questions like "How fast" and "magnitude of". Those are questions where the answer is always positive. You can pick a direction for things to be travelling in if it helps you picture things but it shouldn't affect your answer.

3. Oct 15, 2012

### ArcherofScience

Re: trucks travels beneath an airplane.....

ohh ok. i see. thanks :)....i have another question from my hw......is it ok to ask it on this same thread?

4. Oct 15, 2012

### Dick

Re: trucks travels beneath an airplane.....

Its ok. But it will probably get more attention if you post it in a new thread.