# Help is needed.

I'm about 2 weeks into A.P. Physics, and couldn't be more lost. The teacher told me just to jump into A.P. without taking regular physics. And here I am now, failing the class. Now I have decided to scour the internet, not for the answer, but for something to lead me into the direction.

The question,

A swimmer runs horizontally off a diving board with a speed of 3.63 m/s and hits the water a horizontal distance of 1.58 m from the end of the board.

What I need:
How high above the water was the diving board? (In meters)

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Relevant equations are

v = vo + at
v^2 = vo^2 + 2a(deltax)
x = xo + vot + 1/2at^2

I have no attempted solutions, because I don't know where to even start.

Redbelly98
Staff Emeritus
Homework Helper
Welcome to PF FlippyBP.

Those are the right equations to use, and a good starting point.

Do you know about treating the horizontal and vertical components of motion separately?

I'll suggest starting by looking at the horizontal motion only, since you're given information about the horizontal motion. Try to find all possible relevant quantities using your equations and the given information.

We were taught that, but the teacher did not go into detail. She wrote a ton of letters on the board and started to fill out numbers....

Redbelly98
Staff Emeritus
Homework Helper
Okay. I'm going to ask about something more basic in a moment--I'm trying to understand how much you know.

These types of questions deal with displacement, velocity, and acceleration. Since these are examples of vectors, I'll ask you:

Do you understand the concept of a vector?

And if so, do you know about the 2 ways to describe a vector:

1. By it's magnitude and direction,
or
2. By it's individual components, i.e. x-component and y-component.

I have zero knowledge of vectors.

Redbelly98
Staff Emeritus
Homework Helper
I see.

Well, there's really no way to get around it ... you'll need to understand vectors to understand this type of homework problem, and other stuff that will come up in physics later on in the year.

I'm not sure what your best course of action is at this point. Either gutting it out in this class, which would mean spending extra time to learn concepts like vectors (stuff that I guess the rest of the class had in a previous physics class?) ... or seeing if you can transfer to standard (non-AP) physics. Transferring classes may be possible if you're just 2 weeks into the term, but of course you'd need the teacher's permission.

If you do want to learn about vectors, here's on online link that looks like a good introduction:

http://www.glenbrook.k12.il.us/gbssci/Phys/Class/vectors/u3l1a.html [Broken]

At the bottom of the page, are a series of links that continue the lesson. Try to get through the 1st 4 of these pages linked there, up through and including "Vector Components". If you can get through that, you should then have a pretty good handle on vectors.

It will require some knowledge of trigonometry ... if you're familiar with sine and cosine, plus maybe tangent, that is enough.

After you get through the vector stuff, then come back to this homework problem.

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I could switch out into the regular class, but the teacher said that I have the potential to do great in the class. It's like being thrown off a boat, at first you will flail around and struggle, but you will soon learn to swim............or drown. I am meeting her before school, in hopes that it will help.

Thank you very much for the links, I will check them out.