Physics isn't tight

[IIwhitexb0iII]

I've done well on all of my homework problems sans this current one. Its a projectile motion problem...given the maximum height of a projectile (4.90 m), its range (25.0 m) and the time to hit the ground again (2 s) find the initial velocity and the launch angle. If anyone loves physics and is willing to help, please do.

Thank you very much in advance,
-Michael

ps. If you're interested, I'm on AIM @ ohfiveinyourface...thanks

[beef_bourito]

it's initial velocity is 15.9m/s, at an angle of 38 degrees.

first you find the vertical component of the velocity:
d = Vot + 1/2 a t^2
4.90 = Vo(1) + 1/2 (9.8) (1)^2
Vo = 4.90 + 4.90 = 9.8
the time is 1 because it only takes half the time to get to the top

then you find the horizontal component of the velocity:
V = d/t
V = 25/2
V = 12.5

then use pythagorean theorem to find the actual velocity
V = sqrt (9.8^2 + 12.5^2)
V = 15.9

use your trig ratios to find the angle
tanX = opposite/adjacent
tanX = 9.8/12.5
X = arctan (9.8/12.5)
X = 38 degrees

if you use something other than 9.8 for gravity you'll want to do the calculation yourself with that value

[speediva]

See, I love math... but I never got to take physics...


What's the fun in that???




I wanna take physics. I wonder if my company would foot the bill...

[Oz]

Just take WhiteBoi's, I'm sure you would make his day.

[speediva]

Let me get right on that...


He can deal with all the incompetent tutors I work with. *groan* But wait, does that mean he gets my paycheck, too? Cause that ish isn't cool.

[beef_bourito]

no he's not allowed to teach, apparently there's a rule around here that you can't teach if you can speak english, and since he's shown he has at least some mastery of the language he can not teach english students.

[drunken monkey]

i'm not entirely sure you should've just done his homework question for him.

[speediva]

Originally Posted by drunken monkey

i'm not entirely sure you should've just done his homework question for him.

Actually, he did some of the best tutor practices...

Not only did he show the work, but he explained what each step was for. He assumed, being the course is physics, that some things (like why to use each formula in succession) would be self-explanatory.

[drunken monkey]

but this is still pre-hand-in.
if this was after the fact, maybe but as it is, all that is likely to happen now, is that the answer be copied.

[speediva]

Copied or not, at least it's broken down into pieces.

The idea is that they can see how to obtain the answer, so on a future question, they can follow the same process. That's when student accountability comes into play.

[drunken monkey]

it might be a difference is our teaching systems.
in the UK, you have to show the complete working out which involves a step by step break down as was shown.
If the question was a UK piece of homework, what he posted would've been a model answer.
I guess I would've just prefered it if he hadn't ut in the relevant figures as well. I mean, it would've been more than sufficient to just give the break-down sans numbers.

Call me an old man but in this instance I'd rather have him get the question wrong and learn how to do it afterwards than just get the answer given to him for future reference.

[IIwhitexb0iII]

thank you all very much for your assistance, in a moment of weakness i made the post on the board only to eventually figure it out myself in a similar fashion.

-Michael

[balls_to_the_wall]

I despise Engineering Physics.

[beef_bourito]

what do you mean by that? do you mean you hate physics that are involved in engineering or do you hate the program called angineering physics, engphys for short. they're kind of the outcasts of the engineering faculty here, there are only 10 of them, if they're lucky, and they tend to be slightly off in the head. i like to refer to them as "those people" or if i find out someone is in it i usually respond with "oh, you're one of THOSE".

[balls_to_the_wall]

Thats in reference to the class Engineering Physics I (I'm an EE). Me and physics aren't really getting along to well right now.