Did nobody teach you the STD triangle?
D
S-T
Distance = SpeedxTime
Speed = Distance/Time
Time = Distance/Speed
hurr
D
S-T
Distance = SpeedxTime
Speed = Distance/Time
Time = Distance/Speed
hurr
-Sh1fty- wrote:
Ok but what about the bicycle problem? I'm still sort of lost. Minty helped but I'm still confused.I'm so freaking bad at this. T = time right? So what the hell does 72t mean? 72 * t?A cyclist leaves the town of Ouchy towards Cully at 15:00. His average speed is 18km/h. Another man is walking from Cully to Ouchy and he leaves at 14:30. His average speed is 7.2km/h.
The distance separating the two towns is 10km.
No way I'm ever passing this fucking school, why did I ever take these extra courses? I just wanted to finish a year earlier...
s = ut+0.5at2
s = vt-0.5at2
s = 0.5(u+v)t
v = u+at
v2 = u2+2as
a = (v-u)/t
a=acceleration, t=time, u=initial velocity, v= final velocity, s=displacement.
Only equations you'll ever need. ever.
edit:fucking smilies.
s = vt-0.5at2
s = 0.5(u+v)t
v = u+at
v2 = u2+2as
a = (v-u)/t
a=acceleration, t=time, u=initial velocity, v= final velocity, s=displacement.
Only equations you'll ever need. ever.
edit:fucking smilies.
Last edited by presidentsheep (2010-02-25 15:07:04)
I'd type my pc specs out all fancy again but teh mods would remove it. Again.
right so given t=time-Sh1fty- wrote:
Uhhh yeah well here's another exercise I've got to do, this one is with bikes, maybe this'll help.
A cyclist leaves the town of Ouchy towards Cully at 15:00. His average speed is 18km/h. Another man is walking from Cully to Ouchy and he leaves at 14:30. His average speed is 7.2km/h.
The distance separating the two towns is 10km.
The question is:
At what time and what distance from Ouchy will they cross each other?
let t=0 be 15:00. Time is 0 at 15:00.
We'll call the first cyclist A. He starts at t=0 and his speed is 18km/h.
We'll call the second cyclist B. He starts at t= -00:30 and his speed is 7.2km/h.
To simplify the problem, have them start at the same time. That means multiply out the distance covered by cyclist B until t=0 for both of them. 7.2km * .5h = 3.6km. The distance between the two cyclists at 15:00 is now 6.4km.
Use the equation from the other problem. 18t + 7.2t = 6.4
Simplify. 25.2t = 6.4km
t = .25397h, or (*60) = 15.24 minutes.
At time = 15:15, the cyclists cross. To find the distance from ouchy, simply multiply the time by the rider leaving ouchy. .25397h*18km/h = 4.57km.
I realized I just reiterated everything peter wrote out, but you seem to have some serious comprehension issues. Talk to your teacher and try to get the basic things sorted out such as variables and forming equations.
I just looked at my post and remembered how proud I was of my cyclist diagram.
That's a good diagram.. almost on par with my train crashPeter wrote:
I just looked at my post and remembered how proud I was of my cyclist diagram.
Fairly sure I was taught to write x like that in order to avoid confusion in later life.Bevo wrote:
I don't think I learned the cross or dot product in HS...
and they certainly wouldn't teach vector multiplication BEFORE simple things like velocity and displacement
Was writing x like that since like 3/4 grade. Cause 7xy =/= 7xyliquidat0r wrote:
Fairly sure I was taught to write x like that in order to avoid confusion in later life.Bevo wrote:
I don't think I learned the cross or dot product in HS...
and they certainly wouldn't teach vector multiplication BEFORE simple things like velocity and displacement
Last edited by DrunkFace (2010-02-26 00:45:29)
Just need to work out the closing speed (=Speed A + Speed B) and the distance travelled.
Fuck Israel
Thanks a lot for your help guys. I'm off to do my test now. I hope I do well, sucks they give me a test right after vacation.
And above your tomb, the stars will belong to us.
No one taught me that... and I am glad.Finray wrote:
Did nobody teach you the STD triangle?
D
S-T
Distance = SpeedxTime
Speed = Distance/Time
Time = Distance/Speed
hurr
Stupidest thing I have seen in a long time.
Its very very basic algebra. If you need a special triangle to remember how to algebraically manipulate an equation that easy you got MUCH bigger problems.
yeah, i used to write x as a cross but i eventually became so annoyed because i kept mixing up x and * in like 10xy or 10*y that i decided to do the curly version (although my handwriting is always fairly curly)liquidat0r wrote:
Fairly sure I was taught to write x like that in order to avoid confusion in later life.Bevo wrote:
I don't think I learned the cross or dot product in HS...
and they certainly wouldn't teach vector multiplication BEFORE simple things like velocity and displacement
The paradox is only a conflict between reality and your feeling what reality ought to be.
~ Richard Feynman
~ Richard Feynman
good luck with the test, wish I could've helped but was never good at physics, I was better at maths... was ok for the most part.....-Sh1fty- wrote:
Thanks a lot for your help guys. I'm off to do my test now. I hope I do well, sucks they give me a test right after vacation.
Why would you ever write out 10*y?Spark wrote:
yeah, i used to write x as a cross but i eventually became so annoyed because i kept mixing up x and * in like 10xy or 10*y that i decided to do the curly version (although my handwriting is always fairly curly)liquidat0r wrote:
Fairly sure I was taught to write x like that in order to avoid confusion in later life.Bevo wrote:
I don't think I learned the cross or dot product in HS...
and they certainly wouldn't teach vector multiplication BEFORE simple things like velocity and displacement
Coefficients are pretty much always just written as 10y. I have never seen any text book, assignment, test, hand out, example, ect... written as 10 X Y as in 10 times Y. It's just not done for that very reason.
i don't know i just made that up on the spot didn't i? the point is i changed because i was getting x and * mixed up.VicktorVauhn wrote:
Why would you ever write out 10*y?Spark wrote:
yeah, i used to write x as a cross but i eventually became so annoyed because i kept mixing up x and * in like 10xy or 10*y that i decided to do the curly version (although my handwriting is always fairly curly)liquidat0r wrote:
Fairly sure I was taught to write x like that in order to avoid confusion in later life.
Coefficients are pretty much always just written as 10y. I have never seen any text book, assignment, test, hand out, example, ect... written as 10 X Y as in 10 times Y. It's just not done for that very reason.
The paradox is only a conflict between reality and your feeling what reality ought to be.
~ Richard Feynman
~ Richard Feynman
Unless if you actually study physics on a higher level than junior high. That's just the most basic stuff for mechanics.presidentsheep wrote:
s = ut+0.5at2
s = vt-0.5at2
s = 0.5(u+v)t
v = u+at
v2 = u2+2as
a = (v-u)/t
a=acceleration, t=time, u=initial velocity, v= final velocity, s=displacement.
Only equations you'll ever need. ever.
edit:fucking smilies.
Last edited by DeathUnlimited (2010-03-01 04:14:23)
main battle tank karthus medikopter 117 megamegapowershot gg
while there's a thread for this, i might just lay down my own problem
An athlete, commencing at a point due east, completes a half lap of a 440m track in 25s. Determine the athlete's:
- average velocity (in a westerly direction)
An athlete, commencing at a point due east, completes a half lap of a 440m track in 25s. Determine the athlete's:
- average velocity (in a westerly direction)
I FAAAAAAAAAAAAAAAAAAAAAAAAAAAAAIIIIIIIIIIILED
No jk
I did ok but just "OK"
That teacher is such a faggot anyway, he loves throwing shit in we never studied, and when we ask for help he says we're young idiots who're too stupid to look stuff up ourselves and cuts us off when we try to explain.
Anyway, fuck him
But yeah I'd like to thank you all for the great help! Without you I would have flunked for sure!
No jk
I did ok but just "OK"
That teacher is such a faggot anyway, he loves throwing shit in we never studied, and when we ask for help he says we're young idiots who're too stupid to look stuff up ourselves and cuts us off when we try to explain.
Anyway, fuck him
But yeah I'd like to thank you all for the great help! Without you I would have flunked for sure!
And above your tomb, the stars will belong to us.
Well, really it depends on where he started and the shape of the track, and how they position NSEWGravityy wrote:
while there's a thread for this, i might just lay down my own problem
An athlete, commencing at a point due east, completes a half lap of a 440m track in 25s. Determine the athlete's:
- average velocity (in a westerly direction)
Assuming North is up and west is left, and the track is round...
You go 180 degrees around the circle, then find the horizantal distance from starting point to finishing point and divide by time.
So if he starts at the top of the track, he makes it to the bottom, and average velocity is 0, because only taking his horizantal motion into consideration he ran off to the side, then back, and the velocity vectors in the second half cancel those in the first.
If he starts at the side of the track, he runs half way around to the other side, and his horizontal motion is equal to the diameter, and velocity is that distance divided by the time it took. If 440m is the circumference the diameter is 440/pi or about 140m/25 to give like 5.6m/s
If his starting point is at some angle Ø from the east-west axis then his displacement is (440/pi)*cos(Ø)/25, which is basically the radius times the cosine of the angle doubled to give the twice the horizontal distance from the center to the starting point divided by the time.
Pfffffft, I've nearly finished A-Level's and everything seems to boil down to these equations (Well... Three of them) after a while.DeathUnlimited wrote:
Unless if you actually study physics on a higher level than junior high. That's just the most basic stuff for mechanics.presidentsheep wrote:
s = ut+0.5at2
s = vt-0.5at2
s = 0.5(u+v)t
v = u+at
v2 = u2+2as
a = (v-u)/t
a=acceleration, t=time, u=initial velocity, v= final velocity, s=displacement.
Only equations you'll ever need. ever.
edit:fucking smilies.
I'd type my pc specs out all fancy again but teh mods would remove it. Again.
For general physics. Have fun with quantum theory.presidentsheep wrote:
Pfffffft, I've nearly finished A-Level's and everything seems to boil down to these equations (Well... Three of them) after a while.DeathUnlimited wrote:
Unless if you actually study physics on a higher level than junior high. That's just the most basic stuff for mechanics.presidentsheep wrote:
s = ut+0.5at2
s = vt-0.5at2
s = 0.5(u+v)t
v = u+at
v2 = u2+2as
a = (v-u)/t
a=acceleration, t=time, u=initial velocity, v= final velocity, s=displacement.
Only equations you'll ever need. ever.
edit:fucking smilies.