Kind: captions
Language: en
Today I'm going to bake this chocolate
cake. Now those of you who know me know
that the only reason I would do this is
to prove a point. Earlier I was asking
people to compare the temperatures of
these two objects. A science book
written by Isaac Asimov and an old metal
hard drive.
Can you compare their temperatures?
This one I think.
Yeah, that feels colder.
Cold and it's room temperature.
Can you tell me?
You would say colder than that one?
Yeah. What makes something hotter or
colder? What what affects that?
The the actual material. I mean, paper
is warm and metal is cold.
Both of these objects have been sitting
here on the ground for quite a while.
So, one might expect that they're at the
same temperature.
No, because this is a metal and that's
paper.
But what if I left that outside all day?
Would it be 15°?
No, because paper doesn't absorb cold.
Doesn't absorb cold.
No. Well, I've left books out, not all
day, um, outdoors, and I can't say that
I've noticed the book was cold when I've
come to pick it up ever.
What if I told you that these two
objects are actually the same
temperature? What would you say?
Definitely not. If it's temperature
right now, this is colder.
So, let's say you're taking a cake out
of the oven.
Yeah.
Would you be uh worried about touching
the cake?
Yes. Well, not the cake itself, but the
actual teen around the cake, cuz it'll
be hot.
Yeah. But how does the temperature of
the tin compare to the temperature of
the cake?
Well, the cake will be warm, like hot,
but not as hot as a tin.
The tin's hotter because it's metal.
Metal metal holds the heat longer and
holds the cold longer.
Do you think the tin would be the same
temperature as the cake?
Well, you think it if it's been like in
200° C, it'd be the same. But it's
somehow it just doesn't feel like it
will burn with metal whereas my fingers
will melt. But I mean, not if I stick my
finger in the cake, it wouldn't burn as
much. All right, it's time to take the
cake out and find out if it's the same
temperature as the tin. I have a meat
thermometer with which to measure the
the temperature of the cake. I'm not
sure that's the most accurate way of
doing it, but well, it's the only thing
I've got. So, let's give it a shot. So,
I tried to measure the temperature of
the cake using a meat thermometer, but
unfortunately, its temperature scale
doesn't go high enough to allow me to
accurately measure the temperature of
the cake. You can actually hear the
moment when I realized that my
experiment wasn't going to work.
Uhoh.
So, now I'm back in Vancouver and I
thought I'd bring in the big guns to
help me sort out this experiment. And by
the big guns, I of course mean uh my
mom.
So, Derek, I understand we're going to
make this vanilla cake mix together and
see what happens.
We've got a secret weapon, which is this
infrared thermometer, which can measure
temperatures up to 300° C. So, we should
have no problems with it. We just point
it at a surface and it gives us a
readout of the temperature of that
surface. So, this should be perfect for
measuring the temperature of the cake
and the tin. Do you want to make a a
prediction about the relative
temperatures of the cake and the tin
when we bring it out of the oven?
Well, I really suspect that the tin is
going to be a lot hotter than the cake.
You can really not handle the tin at
all. So, I I reckon that's what's going
to happen.
Okay. Well, I think they're both going
to be the same temperature, but I could
be wrong. So, we're going to have to do
the experiment and find out.
All right, let's get mixing.
Okay, so it's been about a half an hour
and the cake is cooked. It's ready to
come out.
Yeah, we're all ready to go.
That is your your expert opinion as the
master baker here. [laughter]
Yes, I think so.
Okay, we're going to take the cake out
of the oven and we're going to check the
temperature of the tin and the cake.
Let's do it.
Okay.
Ooh, it looks like a good cake.
Yeah, not a bad one. Okay. So, let's
measure the temperature of the cake. We
have
108.9
and the temperature of the tin
118.6
but dropping
over here
108.1.
So, we have uh what would you say about
the temperature of the cake and the tin?
Pretty close. Much closer than I
expected.
H. They're quite similar. They're both
around 110
uh Celsius. That's my point is that the
tin and the cake are the same
temperature, but the tin is going to
conduct heat to your hand much faster
than the cake. So, the tin would burn
you, but the cake would not, but they're
the same temperature. What if I were to
impress upon you that they are in fact
the same temperature?
I'll take your word for it.
And and that in fact that these two are
the same temperature.
Yeah, I don't agree with that.
No,
you don't think those are the same
temperature?
No.
Really? I just can't believe this book
is 15°. It just doesn't feel it.
[laughter]
I just can't believe it. In truth,
there's no difference in the temperature
between these two objects. If they've
been in the same surroundings for a long
period of time, they come to thermal
equilibrium with their surroundings,
which means they're both at the same
temperature. But the metal feels colder
because it's able to conduct heat away
from my hand faster than the book. So,
just because an object feels colder,
that doesn't mean that it actually has a
lower temperature. It may just mean that
it's conducting heat away from your hand
faster.
I see. Oh, that's interesting. I just
learned something. [laughter]