Shelagh: Well here's another equation for you to have a go at. This time q is another energy. m is a mass.

Alison: Yeah.

Shelagh: c is something called the specific heat capacity. T is temperature.

Alison: Yeah.

Shelagh: And this delta denotes a change in temperature, so you can't separate the delta from the T, it's just one term ...

Alison: Right.

Shelagh: ... delta T.

Alison: Right. Right.

Shelagh: And this time why don't you try and find c, make c the subject.

Alison: Okay.

Shelagh: So what would be a good way to start.

Alison: Um, I could, er, reverse the equation, er, like this, to get ... c on the left-hand side.

Shelagh: Yes.

Alison: It's not on its own though. [Laughter]

Shelagh: [Laughter]. No, and this time it's multiplied by m and by delta T so you've got two things to get rid of.

Alison: Yeah. Yeah.

Shelagh: But you don't need to get rid of them both at once. Do, do one first and then the other.

Alison: Okay.

Shelagh: So, choose.

Alison: I could start by dividing by m.

Shelagh: Yes.

Alison: Both sides by m.

Shelagh: Yes.

Alison: Okay, er, so if I do that over m and q over m.

Shelagh: Yes.

Alison: Then those two ms cancel so I'm left with c delta T is equal to q over m.

Shelagh: Great. Okay, so we're half way there.

Alison: Yeah.

Shelagh: Now you've got to get rid of the delta T.

Alison: Yes, so I will divide by delta T on both sides as well.

Shelagh: Yeah.

Alison: So I'll do c delta T divided by delta T ...

Shelagh: Yes.

Alison: ... is equal to q over m divided by delta T.

Shelagh: ... divided by ... Excellent. Yes and you put the delta T on the bottom of the fraction ...

Alison: Yeah.

Shelagh: ... which is exactly what you want because it's doing the dividing.

Alison: Lovely. So then I can cancel these two delta Ts out and I'm left with c is equal to q over m delta T ...

Shelagh: Brilliant. You've done it.

Alison: ... which is what I wanted. Great.

Shelagh: Excellent.

Alison: [Big sigh].

Narrator: Let's look again at the hints used this time. Once again she started by reversing the equation to get the subject, c on this occasion, into place on the left-hand side.
After that, she had to get rid of two terms, m and delta T, and did this one step at a time. You should never be afraid of using several small steps to rearrange one equation.
To get rid of both the m and the delta T, Alison had to remember that the c was multiplied by those terms and so divide by them. And she had to divide BOTH sides of the equation by first m and then delta T.