A few days ago
Anonymous

physics math help?

can anyone guide me through the following problems. It is my first time taking physics and i do not know how to solve these types of problems. thanks

1. (p1/t1) = (p2/t2) (solve for p2):

2. pv = nrt (solve for r):

Top 4 Answers
A few days ago
blueskies

Favorite Answer

PROBLEM 1:

p1 …. p2

—- = ——

t1 ……t2

cross multiplying… you get…

p2 * t1 = p1 * t2

now divide both sides by “t1″…. and you get

p2 * t1 ….. p1 * t2

——— = ————

…t1 ………….t1

on the left side, the t1’s cancel…. leaving you with…

p2 = (p1 * t2) / t1

So far we haven’t done anything physics-related…. this was just plain algebra…. It’s a physic formula, but you are using your algebraic math skills to manipulate the formula so that you have “what you want to find” on the left…. and then the elements that you are going to use to calculate p2 are on the right side…

2. pv = nrt

Okay… we want to solve for “r” now…

Well…

Another way of writing pv = nrt, is nrt = pv, right?

Because pv and nrt are equivalent to each other… it doesn’t really matter if you write it…

pv = nrt…. or nrt = pv…. but because we are solving for “r”… I wanted it to be on the left side…

so….

pv = nrt…. became… nrt = pv….

Now how do you get “r” alone on the left side? Do you know?

Well, to get “r” alone… we divide BOTH sides by “nt”… like this…

nrt …. pv

—- = ——

nt …….nt

So that… the n’s and t’s cancel on the left leaving you with “r”…. and so you have…

r = (pv) / (nt)

DONE!!!! :o)

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A few days ago
Anonymous
What you want to do is manipulate the equations, by dividing or multiplying a variable on both sides, so you can isolate the single variable of choice.

1. p1/t1 = p2/t2 —> mutiply both sides by t2, so the right side cancels out.

p1*p2 / t1 = p2

2. pv = nrt –>divide everything except for the r on the right side, so you can isolate the r.

r = pv/nt

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A few days ago
wayner122
1. You want to solve for p2 which means you want to end up with p2 = something. So you are going to unravel the equation by working backwards. Look at the side of the equation that has p2 on it. So you want to move the t2 because if the t2 was gone then we would have our p2 = . So you are dividing by t2 and to undo that you have to multiply both sides by t2. So you will end up with (p1/t1)*t2 = p2.

2. Once again you want to have r = something. So looking at the side with r on it, you see that you want to move the n and the t over. So, you are multiplying r by n and t, so you will have to divide to undo the multiplication. (pv)/(nt) = r.

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A few days ago
navy_bison
(p1/t1) = (p2/t2) multiply through by t2 to get p2 term on one side

(p1/t1)(t2)= p2

pv = nrt divide out nt on each side to get r by itself

pv/(nt) = r

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