Help with Physics? ;-;

basilmarket.com forums : Chat | 15 posts archived

thread starter PriRO3 Oct 04 2010 + PM | QUOTE | PERMALINK | REPORT

Edit: For the sake of not having to make a new thread, I'ma just edit yesterdays ._. I hate the thought of physics homework, I start off well and get everything right off the bat. . But then the last problem comes up and I'm done. Ughhh. Anyways, if you help, thank you for your time. : A stone is thrown vertically upward with a speed of 18.0 m/s.. (assume this is inside a vacuum.) a.) How fast is it moving when it reaches a height of 110m? b.) How long is required to reach this height? Why are there two answers? ATM, I'm stuck on A. What I have so far is. . Vi=18.0 m/s Vf=? dy=110m g=9.8 m/s^2 Do I leave both dy and g positive, or do I make one negative? I tried both of those options, but I still CAN'T get it right =.= Anyways.... I used Vf^2=Vi^2+2gdy Vf^2=(18.0 m/s)^2+2(-9.8m/s^2)(110m) Vf^2=324 (m/s)^2 + (-2156 m/s)^2 . . . . imaginary number. And even if it was positive Vf^2=324 (m/s)^2+ 2156 (m/s)^2 Vf^2=2480 (m/s)^2 Vf= 50 m/s (The velocity RAISED? -__- AHH, HELP PLEASE D:

My Characters: Oblivion0x - 82 Bera White Knight

SilentXynh 10/04/10 + PM | QUOTE | PERMALINK | REPORT

I'm not in the state of mind to attempt this question, but try working in metres. Do m/s instead of km/h.

My Characters: Aussenritter - 90 Scania Dawn Warrior

PriRO3 + PM | QUOTE | PERMALINK | REPORT

[quote] SilentXynh : I'm not in the state of mind to attempt this question, but try working in metres. Do m/s instead of km/h. [/quote] Will doo. .-. Now I ended up with -248.1 m/s^2 =) Thanks a ton. xD

My Characters: Oblivion0x - 82 Bera White Knight

Gumbells 10/04/10 + PM | QUOTE | PERMALINK | REPORT

I'm surprised you do your homework.

My Characters: Rouste - 33 Khaini Blade Acolyte

CHa0sS1n 10/04/10 + PM | QUOTE | PERMALINK | REPORT

[quote] PriRO3 : Will doo. .-. [/quote] That's actually the only reason you went wrong in your calculations. The formulas in physics use SI units whereas you didn't use them. If you convert km/h into m/s by dividing km/h by 3.6, you should come out with a m/s that will give you a correct looking answer. Just plug into the kinematic equations and you should be fine.

My Characters: xcha0sinx0 - 50 Broa Assassin

FirezRage + PM | QUOTE | PERMALINK | REPORT

ok im not sure if i'm putting in the right numbers for this question, but i'll give it a try s=(v+u/2)t u = 85km/h --> 23.61.. (recurring 1)ms^-1 v = 0 s = 0.8m t = ? rearranging the equation to find t (time) is: t= (2/u+v)s t= 144/2125 v = u+at rearranges to give a = v-u/t a= -23.61..(recurring)/(144/2125) a= -348.43 ms^-2 now since u want to find it in terms of g then -348.43/9.81 = -35.5 g EDIT: ohh i see ur units are all in km/h whereas i'm used to things in ms^-1

My Characters: AranDavee - 81 Windia Aran in Misery

PriRO3 10/04/10 + PM | QUOTE | PERMALINK | REPORT

[quote] CHa0sS1n : That's actually the only reason you went wrong in your calculations. The formulas in physics use SI units whereas you didn't use them. If you convert km/h into m/s by dividing km/h by 3.6, you should come out with a m/s that will give you a correct looking answer. Just plug into the kinematic equations and you should be fine. [/quote] Thank you, I'll remember that. =)

My Characters: Oblivion0x - 82 Bera White Knight

ImALowStr 10/04/10 + PM | QUOTE | PERMALINK | REPORT

0.o this stuff looks hard what grade is it ?

My Characters: ShootBlind - 106 Yellonde Ranger

PriRO3 10/04/10 + PM | QUOTE | PERMALINK | REPORT

[quote] ImALowStr : 0.o this stuff looks hard what grade is it ? [/quote] Don't troll, makes me fell shtoopid ;-; But if you're not, I'm a Junior. Honors Physics. . o.o

My Characters: Oblivion0x - 82 Bera White Knight

Reskho 10/04/10 + PM | QUOTE | PERMALINK | REPORT

if you convert everything to SI units, you end up with a = -348 m/s^2 which is like what, 35 G's? or maybe I have no idea what I'm talking about. Possibly the latter.

My Characters: BriskAurora - 73 Scania I/L Mage

PriRO3 10/04/10 + PM | QUOTE | PERMALINK | REPORT

[quote] Reskho : if you convert everything to SI units, you end up with a = -348 m/s^2 which is like what, 35 G's? or maybe I have no idea what I'm talking about. Possibly the latter. [/quote] No, you're very right. xD -35.5 g.

My Characters: Oblivion0x - 82 Bera White Knight

xs2xx 10/04/10 + PM | QUOTE | PERMALINK | REPORT

O: I'm learning the exact same thing too! Except, I'm not in honours .

My Characters: xBBTEA - 101 Bera I/L Mage

2Samuel + PM | QUOTE | PERMALINK | REPORT

I'm in Honors Physics too. Except we're learning projectiles, not this. Sorry. :/

My Characters: 2Samuei - 139 Khaini Shadower

PriRO3 + PM | QUOTE | PERMALINK | REPORT

[quote] xs2xx : O: I'm learning the exact same thing too! Except, I'm not in honours . [/quote] =3 we did Graphical analysis today, test on thursday, we start chapter 3 tomorrow. above Are you a jr or a sr? ;o Plan on taking AP Physics? I Plan on it if I manage to get a B+ or higher, and so far that doesn't seem like it'll be a problem.

My Characters: Oblivion0x - 82 Bera White Knight

lilAznSader 10/04/10 + PM | QUOTE | PERMALINK | REPORT

What's all this junior and senior business @_@ Here in Canada, we just call it by grade. Like 6th grade, or Secondary 4, etc. Explain please :D

My Characters: HawkSlinger - 62 Khaini Gunslinger