quick astb question

[contradickshon]

Hey,

I'm taking the ASTB in a couple of weeks and have been studying the Marine Corps ASTB study guide on this site--wonderful resource by the way. Thanks. This question is killing me...

...mechanical comp question (4) which asks: "If you had to swim across a fast moving stream exactly perpendicular to the banks, when you arrived at the far bank where would your position be relative to where you started across?"

And then the multiple choice answers are not in alphabetical order.

I find the question ambiguous. I have a feeling the principle of the question has something to do with crosswind landings and crabbing, but is downstream the answer? This is driving me nuts...

 

[Daedalus]

Yes the answer is downstream. If you are swimming straight across and the water current is pushing you to the left (as warer is flowing right to left) you will be downstream from where you started even though you are going straight.
Think of it as that game frogger. You go straight across the road but a car hits you and pushes you left.

 

[FlyingJ2003]

Is the ASTB exam the same for both the Marine Corps and the Navy? DO they take similar, but diferent exams?

 

[Eteled]

Daedalus is correct, but you should think of it in terms of what it is. That way you can apply it to other situations... They're called perpendicular vectors. Perpendicular (orthogonal) vectors do on effect each other. That is to say, swimming forward will not change your side (perpendicular) motion.

 

[Penguin]

I think you had the right idea to begin with. Yes, your nose is pointed directly across the stream, but the current pushes you downstream the whole time you are crossing. This is a vector question as stated above, but vectors get pretty tricky without a diagram. If you're really interested in how they work, check a physics text or do a net search.
LTJG G.

 

[contradickshon]

I think I understand what's going on here. Your vector must remain perpendicular to the opposite bank causing your path to angle downstream becuase the vector force of the water current affects your course. The question isn't asking for you to make a perpendicular path but to keep a perpendicular vector.

Thanks Guys

 

[ea6bflyr]

Yes, the ASTB is the same for Navy and Marine Corps.
ea6bflyr

Originally posted by FlyingJ2003
Is the ASTB exam the same for both the Marine Corps and the Navy? DO they take similar, but diferent exams?