### Lecture 13 Slides

```Heat is defined to be
A.
B.
C.
The amount of microscopic translational
and rotational kinetic energy in an
object
Energy that is transferred to an object
because of a temperature difference
The temperature of an object in terms
of degrees Kelvin.
Energy transferred (Q)
Q  CT
Q  mc  T
200 g of water at 100o is poured into 200 g
of water at 0o. The resulting temperature
will settle down to be
A.
B.
C.
D.
E.
0o
50o
100o
Greater than 50o but less than 100o
Less than 50o but more than 0o
cwater=4186 J/kg oC
cgold=129 J/kg oC
I use a heating element to put heat into a kg of
water and a kg of gold at the same rate. Which
changes temperature faster?
A.
B.
C.
1 kg water
1 kg gold
They both heat up at
the same rate.
Q  mc  T
Q is energy transferred
Put 100g Al at 100o C into 500g water at 20o
C. What is the final T?
What will the final T be?
1.
2.
3.
4.
5.
100o
97o
20o
23o
60o
cAl = 900 J/kg oC
cH2O = 4186 J/kg oC
You put 0.4 kg of lead into a
bucket containing 1.2 kg of pure
acetone. Why in the world did
you do that?
Idolatry (Even non-believers find
something to believe in)
"As I study ancient scripture, I am more and more
convinced that there is significance in the fact that the
commandment 'Thou shalt have no other gods before me'
is the first of the Ten Commandments." - President Spencer
W. Kimball (Aug 1977 Ensign)
It also takes energy to melt a
solid or turn a liquid into gas
Q  mL
Latent heat of fusion vs. vaporization
You place equal weights of ice (at 0o C) and boiling
water (at 100o C) into a well-insulated container.
What is the final temperature.
A.
B.
C.
D.
0o C
Between 0o
and 50o C
50o C
Between 50o C
and 100o C
Lf
Lv
c
3.33x105 J/kg
2.26x106 J/kg
ice
2090 J/kg·oC
water 4186 J/kg·oC
steam 2010 J/kg·oC
Q  mc  T
Q  mL
You place a mass mi at temperature Ti into a
mass mw of water at temperature Tw. What
will be the final temperature, and how much
ice will there be?
You place equal weights of ice (at -20o C)
and water (at 0o C) into a well-insulated
container. How much boiling water must be
added to produce only water at 0o C.
Lf
Lv
c
3.33x105 J/kg
2.26x106 J/kg
ice
2090 J/kg·oC
water 4186 J/kg·oC
steam 2010 J/kg·oC
```