Download Physical Sci. Unit 4 Study Guide

Physical Sci. Unit 4 Study Guide
Chapter 15
1. Energy in the form of motion is Kinetic energy.
2. A rock at the edge of a cliff has Gravitational Potential energy
because of its position.
3. Energy that is stored is Potential energy.
4. Energy stored in food you eat is Chemical Potential energy
5. Mechanical energy is the total potential and kinetic energy in a
system.
6. Elastic Potential energy is stored in a stretched rubber band.
7. A book sitting on a shelf has Gravitational Potential energy.
8. Gravitational potential energy depends on the Mass, Gravity, &
height (3 things)
9. The primary source of the sun's energy is Nuclear Energy
10. A pendulum is swinging back and forth and has a kinetic energy
of 400 J at a particular point in its path. Which of the following
statements is not true?
a) Both the kinetic and potential energy are decreasing
b) When the kinetic energy is zero, the potential energy will be
400 J greater
c) The minimum kinetic energy is zero
d) The potential energy increases when the kinetic energy decreases
11. The law of conservation of energy states that energy cannot be
created nor destroyed.
12. Increasing the speed of an object (increases / decreases / does
not affect) its potential energy.
13. Increasing the speed of an object (increases / decreases / does
not affect) its Kinetic energy
14. The SI unit for energy is the Joule
15. You can calculate kinetic energy by using the equation ½ m v2.
16. You can calculate gravitational potential energy by using the
equation mgh.
17. A lawn mower transfers chemical potential energy(fuel) into
mechanical energy so that the mower moves. Some of the
energy is converted to thermal energy in the motor.
18. On a swing your potential and kinetic energies change, but your
mechanical energy does not.
19. When you run, your body has converted chemical potential
energy(food) into mechanical energy(motion) and thermal
energy(heat)
Chapter 16
20. As the temperature of mercury inside the thermometer
increases, its volume increases. (thermal expansion)
21. Energy is transferred as heat from a substance at (low / high)
temperature to a substance at (low / high) temperature.
22. Objects must be (different / same) temperatures in order for heat
transfer to occur.
23. Heating by convection can occur through (solids / liquids /
gasses ).
24. Radiation is the only method of energy transfer that can take
place in a vacuum.
25. Define insulator and conductor.
Insulator- does not allow or barely allows heat to travel through
it. (has a high specific heat)
Conductor- heat easily travels through it. (has a low specific
heat)
26. What is –175ºC on the Kelvin scale? -175 + 273 = 98K
K-273 = celcius
ºC + 273 = Kelvin
27. As the kinetic energy of the molecules in a substance increases,
the temperature increases.
28. The transfer of energy by the movement of fluids or gases with
different temperatures is called convection
29. Energy from the sun reaches Earth by Radiation
30. Convection currents rise in air because warm air becomes less
dense than the cooler air.
31. Which method of energy transfer does not involve movement of
matter? Radiation
32. How much heat energy will cause the temperature of 7 kg of
carbon to increase its temperature by 15 K? The specific heat of
iron is 449 J/kg K. 7kg x 15K x 449 = 47,145J
33. A cold-blooded reptile basks on a warm rock in the sun. Its
body is warmed by (convection / conduction/ Radiation)
34. As the cart goes down a hill of a roller coaster PE is converted
to KE. Some of the energy is said to be “lost”. Explain why
energy is not truly “lost”. Some of the energy turns into sound
energy and heat energy due to friction. Energy is never lost, it
only transfers into another form of energy.
35. Temperature is a measure of the average kinetic energy of all
the particles within an object.
36. A(n) thermometer is a device for measuring temperature
37. Absolute zero is the temperature at which the particles in an
object stop moving.
38. The energy transferred between two objects because of the
temperature difference between the two objects is called Heat.
39. Conduction is the energy transfer as heat between particles as
they collide within a substance or between two objects in
contact.
40. Convection is the transfer of energy by the movement of fluids
with different temperatures.
41. As the temperature of a substance rises how to the particles of
that substance behave? The particles move faster
42. Radiation is the transfer of energy by electromagnetic waves.
43. A(n) Conductor is a material through which energy can be
easily transferred as heat.
44. A(n) insulator is a material that is a poor energy conductor.
45. Specific heat is the amount of energy transferred as heat that
will raise the temperature of 1 kg of a substance by 1 K.
Specific Heats at 25°C
Substance
c (j/kg•K)
Substance
c (j/kg•K)
Water (liquid)
4186
Copper
385
Steam
1870
Gold
129
Ammonia (gas)
2060
Iron
449
Ethanol (liquid)
2440
Mercury
140
Aluminum
897
Lead
129
Carbon (graphite)
709
Silver
234
46. Which substance from the table would be a good insulator?
_water A good conductor? mercury or lead___
47. Does it take more energy as heat to raise the temperature of
water by one degree than to raise the temperature of steam by
the same amount?(see table) Explain. Yes b/c the specific heat
of water is 4186 and steam is 1870, therefore water requires
more heat to increase its temperature by 1 degree.
48. Using the table, determine which substance can absorb the most
energy in a temperature increase of 1K. Water
49. Which substance has a specific heat approximately 10 times
greater than the specific heat of silver? (use the table) Ethanol
50. 10 kg of a substance underwent a 3 K change in temperature
when 11 500 J of energy as heat was added to the substance.
What is the substance?(solve for Cp then use the table from
above to find the substance)
11,500 J / 10kg x 3K = 383=Cp
The substance must be copper