L32_InternalEnergy.ppt gravitational potential

dADa

1. Types of Energy
Gravitational Potentialmgh
Kinetic ½mV
2
Spring Potential ½kx
2
Rotational ½Iω
2
Friction??
system

2. Internal Energy, U
the energy associated with
the microscopic
components of the system
It includes kinetic and potential
energy of translational, rotational
and vibrational motion of the
atoms or molecules

3. Friction
Internal Energy, UTemperature, T

4. •Joules
•Calorie
A historical unit
A Calorie (food calorie)
is 1000 cal
•1 cal = 4.186 Joules
Internal Energy, UTemperature, T
1K = 1°Celsius
Fahrenheit
Reaumur
0°Celsius
100°Celsius
0 K = -273.15°C

5. Heatis a mechanism by
which internal energy is
transferred form one
object to another
because of a
temperature difference
between them.

6. U ~T
Other variables?
ΔU ~ΔT
1.Amount of material
(mass or volume)
2.Material property to
change temperature
ΔU ~m
ΔU ~mΔT
ΔU =CmΔT
SPECIFIC HEAT
or
SPECIFIC HEAT
CAPACITY

7. Tm
Q
c

 Units
J / kg °C
cal / g
°C
is the amount of energy
required to change the
temperature of unit mass by
1°Celsius.
Specific Heat

8. Cup A contains 100 grams of
water and cup B contains twice
as much water. The water in
both cups was initially at room
temperature 25°C. Cup A was
heated to 75°C and cup B was
heated to 50°C.
Which cup had more heat
energy transferred to it?
Cup A
Cup B
The same
ΔU =CmΔT

9. Cup A contains 100 grams
of water at 0°C and cup B
contains 100 grams of
water at 50°C.
The contents of the two
cups are mixed together in
an insulated container (no
heat can transfer in or out).
What is the final
temperature of the water in
the container?
A) Lower than 0°C
B) 0°C
C) between 0°C and 25°C
D) 25°C
E) Between 25°C and 50°C
F) 50°C
G) Higher than 50°C

10. Cup A contains 100 grams
of water at 0°C and cup B
contains 200 grams of
water at 50°C.
The contents of the two
cups are mixed together in
an insulated container (no
heat can transfer in or out).
What is the final
temperature of the water in
the container?
A) Lower than 0°C
B) 0°C
C) between 0°C and 25°C
D) 25°C
E) Between 25°C and 50°C
F) 50°C
G) Higher than 50°C

11. Table,
specific heat

12. Heatis a mechanism by
which internal energy is
transferred form one
object to another
because of a
temperature difference
between them.

13. The water in a cup is initially at
55°C, and the cup is in a room
where the temperature is 25 °C.
A

14. HW. Chapter 11.1, 11.2, 11.3
Quizzes and Examples!!!
Problems 2, 10, 16, 24