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Ensure
Jul 29, 2007, 02:06 AM
1. If watts = joules/seconds find joules

2. if kWh=kwxhours, find kw

3. If R = p*/a find *

4. if e = 1/2 mV2 find v

5. If p= mgh/t , find g

Ive tried to do these and basically need to see if my answers match someone that can do them. I never transposed at high school, so therefore don't really know how, appreciated

Capuchin
Jul 29, 2007, 03:47 AM
Just remember that whatever you do to one side, you must also do to the other side.

So I'll do the hardest one here as an example

if e = 1/2 mV2 find v

E = \frac{1}{2}mv^2

Multiply both sides by 2

2E = mv^2

Divide both sides by m

\frac{2E}{m} = v^2

Take square root of both sides

\sqrt{\frac{2E}{m}} = v

By using this method, it's very easy to transpose any formula with very few errors.

Ensure
Jul 29, 2007, 11:30 PM
1. If watts = joules/seconds find joules - not sure if correct

I come up with joule= watts/seconds ?

2. if kwh=kw x hours, find kw - Not sure if correct

I come up with kw = 1 x h

3. if R = p*/a , find * - I know this wrong, need to know why

I come up with r/a = p*

4. if p = mgh/t, find g - I know this wrong I don't know how to break it down properly

I come up with like mgh= pt

Capuchin
Jul 29, 2007, 11:33 PM
for 1 you are wrong, you need to multiply both sides by seconds

for 2 you are wrong, where did 1 come from? You need to divide both sides by hours.

for 3 you need to divide both sides by p and multiply both sides by a

for 4 you need to multiply both sides by t, and divide both sides by mh.

Study the example I gave again, it contains all the transformations that you need to do here.
Number 3 is a little weird, you don't normally "find *". * is never used as a variable, it normally indicates some transformation.

Ensure
Jul 29, 2007, 11:37 PM
1. If watts = joules/seconds find joules - not sure if correct

i come up with joule= watts/seconds ?

2. if kwh=kw x hours, find kw - Not sure if correct

i come up with kw = 1 x h

3. if R = p*/a , find * - i know this wrong, need to know why

i come up with r/a = p*

4. if p = mgh/t, find g - i know this wrong i dont know how to break it down properly

i come up with like mgh= pt
But I don't know how to multply it by what, joules/seconds / watts/seconds, this is confusing . Same with th hours one

Capuchin
Jul 30, 2007, 12:09 AM
watts = joules/seconds

multiply both sides by seconds

Watts*seconds = joules*seconds/seconds

now seconds/seconds = 1 so

watts*seconds = joules.

Can you do the same with the rest?

lukivr
Sep 21, 2011, 01:13 PM
I know that I'm a few years late on this answer, but all the info on the net says the same thing so I'm going to attack this a bit differently for those that came here by a search:

Tips on transposing:
Basic terminology
To transpose an equation is to end up with a specific single unknown on one side of an equation with the remaining known elements on the other side of the equation. An equation is a statement between two equal sides. For example:
A = B + C
It is important to recognize the 2 sides of an equation are on either side of the equals sign. This example has the letter A on the left side and B + C on the right side. Since both sides are equal, you can switch the two sides without changing the equation, like this:
B + C = A
I'm sure most people recognize that A=B+C is the same as B+C=A. Why is this important? It's usually easier to move the specific unknown to the left side when solving.

Solving an equation that has only addition or subtraction
For example:
A = B + C Solve for B.
First, rewrite the equation so the unknown is on or part of the left side.
B + C = A
Now, we want B alone on the left side. Right now the left side is B + C. How would you get rid of C? (hint: do the opposite of what is currently being done). In this case C is added to B so then we must subtract it. To keep both sides equal we must do the same thing to both sides.
B + C – C = A – C (above equation with C subtracting from both sides)
This will reduce to:
B = A – C This is now solved for B.


Solving an equation that has only multiplication
For example:
D = EF
It is assumed that two letters beside each other are multiplied. The example could be also written like:
D = E x F
To solve this example for F we would first rewrite the equation so the unknown (F) is on or part of the left side, like this:
EF = D
Now, we want F alone on the left side. Right now the left side is EF. How would you get rid of E? (hint: do the opposite of what is currently being done). In this case E is multiplied to F so then we must divide by E. To keep both sides equal we must do the same thing to both sides.
EF/E = D/E (above equation dividing both sides by E)
Since E/E is equal to 1, this equation will reduce to:
F = D/E This is now solved for F.

Solving an equation that has only division
For example:
C = D/E
To solve this example for D we would first rewrite the equation so the unknown (D) is on or part of the left side, like this:
D/E = C
Now, we want D alone on the left side. Right now the left side is D/E . How would you get rid of E? (hint: do the opposite of what is currently being done). In this case D is divided by E so then we must multiply by E. To keep both sides equal we must do the same thing to both sides.
E x D/E = C x E (above equation multiplying both sides by E)
This will reduce to:
D = CE This is now solved for D.

Solving an equation that with division and multiplication
Example:
B = CD/E Solve for D.
To solve this example for D we would first rewrite the equation so the unknown (D) is on or part of the left side, like this:
CD/E = B
Now, we want D alone on the left side. Right now the left side is CD/E . How would you get rid of E and C? Do this in two steps. Let's pick E first. Right now E is dividing the left side so let's multiply the left side by E (which means you have to do it do both sides to stay equal).
E x CD/E = B x E (above equation multiplying both sides by E)
This will reduce to:
CD = BE
Now we must get rid of C on the left by dividing by C. Do this for both sides to stay equal.
CD/C = BE/C
This will reduce to:
D = BE/C This is now solved for D.



Solving an equation that has the unknown in the denominator
Example:
B = CD/E Solve for E.
Now, we want E alone on the left side, but we have a problem. If we just get rid of C and D we will solve for 1/E not E. E must be above the dividing line to be useful. How can we get E as a regular number? (The real terminology is E is the denominator and we want it as a numerator)
Anytime you are solving for an unknown that is a denominator (the bottom part of a fraction) you must multiply both sides by itself. Like so:
E x B = CD/E x E (above equation multiplying both sides by E)
This will reduce to:
EB =CD
Now we must get rid of B on the left by dividing by B. Do this for both sides to stay equal.
EB/B = CD/B
This will reduce to:
E= CD/B This is now solved for E.