TVTropes Now available in the app store!
Open

Follow TV Tropes

Following

Let's make a homework help thread!

Go To

Fafnesbane Raaagh! Since: Jan, 2011
Raaagh!
#951: May 16th 2011 at 10:15:07 PM

You don't need acceleration for that, actually. Power is just the change of energy divided by the change of time.

Tumbril Since: Feb, 2010
#952: May 16th 2011 at 10:19:34 PM

And to get energy, you know that Potential energy=(mass)(gravity)(height).

Then you can substitute that into the formula to find power because you have the time (2 minutes).

Tumblr here.
Marioguy128 Geomancer from various galaxies Since: Jan, 2010
Geomancer
#953: May 16th 2011 at 10:20:21 PM

[up][up][up]Yeah.

[up][up]I don't really know the change of energy here. Yeah...

[up]Okay, I got the potential energy, what do I do next?

edited 16th May '11 10:21:34 PM by Marioguy128

You got some dirt on you. Here's some more!
Deboss I see the Awesomeness. from Awesomeville Texas Since: Aug, 2009
I see the Awesomeness.
#954: May 16th 2011 at 10:28:16 PM

Power=Energy/Time

And I was specifically referring to gravity as acceleration.

edited 16th May '11 10:29:01 PM by Deboss

Fight smart, not fair.
Marioguy128 Geomancer from various galaxies Since: Jan, 2010
Geomancer
#955: May 16th 2011 at 10:36:45 PM

That's odd. I keep getting 75,000, Which isn't the right answer. Am I missing something here?

You got some dirt on you. Here's some more!
Tumbril Since: Feb, 2010
#956: May 16th 2011 at 10:38:20 PM

Make sure your time is in seconds (since watts=Joules per second).

Tumblr here.
Marioguy128 Geomancer from various galaxies Since: Jan, 2010
Geomancer
#957: May 16th 2011 at 10:41:07 PM

Okay! Thank you! That helped so much!

You got some dirt on you. Here's some more!
Deboss I see the Awesomeness. from Awesomeville Texas Since: Aug, 2009
I see the Awesomeness.
#958: May 16th 2011 at 10:51:09 PM

Yeah, watts is kg*m2/s3.

This essentially results in the power needed to travel at a specific velocity equal to the desired velocity multiplied by the resistance force, in this case weight of the object. This principle can be used horizontally for cars as well, provided you have the friction force.

Fight smart, not fair.
Marioguy128 Geomancer from various galaxies Since: Jan, 2010
Geomancer
#959: May 16th 2011 at 10:53:32 PM

Heh, got it now. Thank you all!

You got some dirt on you. Here's some more!
Fafnesbane Raaagh! Since: Jan, 2011
Raaagh!
#960: May 16th 2011 at 11:08:29 PM

Yeah, my bad. Change in energy / change in time veers into calculus stuff.

Marioguy128 Geomancer from various galaxies Since: Jan, 2010
Geomancer
#961: May 17th 2011 at 10:11:39 AM

Yet another physics question.

A block of mass m with a speed vo on a frictionless surface and collides with another mass M which is initially at rest. The two blocks stick together and move with a speed of (vo/3). In terms of m, mass M is most nearly

You got some dirt on you. Here's some more!
Yuanchosaan antic disposition from Australia Since: Jan, 2010
antic disposition
#962: May 17th 2011 at 4:31:47 PM

Try conservation of momentum.

"Doctor Who means never having to say you're kidding." - Bocaj
Marioguy128 Geomancer from various galaxies Since: Jan, 2010
Geomancer
#963: May 17th 2011 at 4:41:25 PM

Oh, sorry, I already figured it out. Your help is appreciated though.

You got some dirt on you. Here's some more!
Wicked223 from Death Star in the forest Since: Apr, 2009
#964: May 18th 2011 at 12:31:07 PM

I'm trying to solve this matrix problem, and I'm stuck.

Starts here:

(3, 2, -1, 4)(1, 3, -4, -7)(-2)(1, 3, -4, -7)(-3)(1, 3, -4, -7)
(2, -1, 2, 10)->(2, -1, 2, 10)(0, -7, 10, 24)(0, -7, 10, 24)
(1, 3, -4, -7)(3, 2, -1, 4)(3, 2, -1, 4)(0, -6, 3, -12)
(1, 3, -4, -7)
(0, -6, 3, -12)
(0, -7, 10, 24)

edited 18th May '11 12:31:36 PM by Wicked223

You can't even write racist abuse in excrement on somebody's car without the politically correct brigade jumping down your throat!
Ironeye Cutmaster-san from SoCal Since: Jan, 2001 Relationship Status: Falling within your bell curve
Cutmaster-san
#965: May 18th 2011 at 1:38:17 PM

It would be helpful if you posted what the problem was asking for. Are you trying to get the matrix into row-echelon form, or something like that?

I'm bad, and that's good. I will never be good, and that's not bad. There's no one I'd rather be than me.
Wicked223 from Death Star in the forest Since: Apr, 2009
#966: May 18th 2011 at 3:56:07 PM

Yeah, I should've posted that.

I'm trying to solve this system of linear equations, here:

3x + 2y -z = 4
2x - y + 2z = 10
x + 3y - 4z = -7

edited 18th May '11 3:56:14 PM by Wicked223

You can't even write racist abuse in excrement on somebody's car without the politically correct brigade jumping down your throat!
Pseudonym I like it here. from The Keebler Tree Since: Jun, 2009
I like it here.
#967: May 18th 2011 at 4:11:53 PM

Use the last equation and isolate x. And then substitute. You're gonna have to do that twice until you have only one variable.

<(-_-<)(>-_-)> "FUSION HA"
Ironeye Cutmaster-san from SoCal Since: Jan, 2001 Relationship Status: Falling within your bell curve
Cutmaster-san
#968: May 18th 2011 at 4:40:10 PM

Alternatively, you can keep using matrix operations like you have been and subtract the third row from the second one in order to generate a leading entry of 1 in the second row, thereby enabling you to zero out the second entries in the first and third rows.

I'm bad, and that's good. I will never be good, and that's not bad. There's no one I'd rather be than me.
Zizoz Since: Feb, 2010
#969: May 18th 2011 at 5:00:57 PM

Check the third operation; it doesn't look right to me, and I think the numbers will look nicer when it's correct.

Ironeye Cutmaster-san from SoCal Since: Jan, 2001 Relationship Status: Falling within your bell curve
Cutmaster-san
#970: May 18th 2011 at 6:15:05 PM

Oh, wow, yeah, those numbers are waaaaaay off.

I'm bad, and that's good. I will never be good, and that's not bad. There's no one I'd rather be than me.
Wicked223 from Death Star in the forest Since: Apr, 2009
#971: May 19th 2011 at 3:47:28 AM

Does

(1, 3, -4, -7)
(0, -7, 10, 24)
(0, -7, 11, -25)

look better?

You can't even write racist abuse in excrement on somebody's car without the politically correct brigade jumping down your throat!
Carciofus Is that cake frosting? from Alpha Tucanae I Since: May, 2010
Is that cake frosting?
#972: May 19th 2011 at 3:49:53 AM

Why -25?

But yes, apart from that it looks good (but I did not check the calculations very accurately, only what you tried to do).

Now, from this point onwards you know how to proceed?

But they seem to know where they are going, the ones who walk away from Omelas.
Noaqiyeum we must dissent (it/they) from across the gulf of space (Time Abyss) Relationship Status: Arm chopping is not a love language!
we must dissent (it/they)
#973: May 20th 2011 at 3:35:55 PM

Running into troubles with a Java assignment, and I think I need to hire mercenaries for supporting fire because the troubles are just too quick for me to shoot by myself.

The program is supposed to test the validity of ISBN-10s entered by the user, and continue doing so until the user enters "q" or "Q"; for some reason, however, I can't get it to actually test validity, because if I do anything but immediately enter Q the console just does nothing.

This is the relevant part of main():


String s = user.nextLine().toUpperCase();
while(s.length() != 1 && s.charAt(0) != 'Q') {

boolean valid = true;
if(!hypInit(s)) {

System.out.println("INVALID: ISBN may not start or end with a hyphen.");
valid = false;

}
// (All other tests retain the same basic format.)
if(valid) {

if(!checkSum(shy)) System.out.println("INVALID: Checksum test error. At least one incorrect digit.");
else System.out.println("ISBN " + s + " is VALID.");

}
System.out.println("");
System.out.println("Enter next ISBN: ");
s = user.nextLine().toUpperCase();

}

ERROR: The current state of the world is unacceptable. Save anyway? YES/NO
StolenByFaeries Believe from a reprogrammed reality Since: Dec, 2010
Believe
#974: May 20th 2011 at 8:09:42 PM

@ Noa:

I asked my sister about your question and she thinks this:

I think the problem is here.
s.charAt(0) != 'Q'
Because it says charAt(0), isn't it only testing if the 1st char is or is not 'Q'? Shouldn't there be some counter like 'i' that starts at 0, and increases by 1 after every loop so you can test each individual char in the ISBN.

She also says she hasn't done JAVA in over a year so she isn't 100% sure. Doesn't hurt to try it though -shrug-

edited 20th May '11 8:17:05 PM by StolenByFaeries

"You've got your transmission and your live wire, but your circuit's dead." - Media
Noaqiyeum we must dissent (it/they) from across the gulf of space (Time Abyss) Relationship Status: Arm chopping is not a love language!
we must dissent (it/they)
#975: May 20th 2011 at 8:20:03 PM

It's supposed to do that. The actual testing is performed within the loop, which keeps prompting for a new entry until the user exits by typing 'q' (or 'Q'). As long as the entered sequence is not a String consisting of just that, the loop should continue. (Notice that String s is passed to hypInit() to be tested, which is supposed to return either true or false...)

:/ Tell her thanks for me, though.

ERROR: The current state of the world is unacceptable. Save anyway? YES/NO

Total posts: 1,508
Top