1. Physics Staar prep
April 30, 2012

2. Question 1
The heat transfer mechanism operating when a heated fluid rises because it is less dense than surrounding fluids is called ____.
a.radiation b.conduction
c.convection d.advection

3. Answer
c.convection

4. Question 2
The heat transfer mechanism that transfers heat energy by electromagnetic waves is called ____.
a.conduction b.convection
c.advection d.radiation

5. Answer
d.radiation

6. Question 3
The heat transfer mechanism that occurs when an object comes in contact with another object is called ____.
a.radiation b.advection
c.conduction d.convection

7. Answer
c.conduction

8. Question 4
The heat transfer mechanism that transfers warm or cold air by horizontal winds is called ____.
a.conduction b.convection
c.radiation d.advection

9. Answer
d.advection

10. Question 5
John’s warm bowl of soup cools before he eats it all. How does the average kinetic energy of the particles making up the soup change as the soup cools?
a.The average kinetic energy of the particles does not change.
b.The average kinetic energy of the particles decreases.
c.The average kinetic energy of the particles changes unpredictably.
d.The average kinetic energy of the particles increases.

11. Answer
b.The average kinetic energy of the particles decreases.

12. Question 6
Lina’s ice cream melts before she eats it all. How does the average kinetic energy of the ice cream particles change as the ice cream is melting?
a. The average kinetic energy of the particles changes unpredictably.
b.The average kinetic energy of the particles decreases.
c.The average kinetic energy of the particles does not change.
d.The average kinetic energy of the particles increases.

13. Answer
d.The average kinetic energy of the particles increases.

14. Question 7
The ice in Mako’s soda melts as he drinks it. How does the average kinetic energy of the ice particles change while they are melting?
a.The average kinetic energy of the particles changes unpredictably.
b.The average kinetic energy of the particles decreases.
c.The average kinetic energy of the particles does not change.
d.The average kinetic energy of the particles increases.

15. Answer
d.The average kinetic energy of the particles increases

16. Question 8
Haya’s cup of hot tea cools before she drinks it all. How does the average kinetic energy of the tea particles change as the tea cools?
a.The average kinetic energy of the particles does not change.
b.The average kinetic energy of the particles changes unpredictably.
c.The average kinetic energy of the particles increases.
d.The average kinetic energy of the particles decreases.

17. Answer
d.The average kinetic energy of the particles decreases.

18. Question 9
When Jill and Kevin play with a ball outside one morning, they notice that it is slightly flat. When they play with the ball later in the day after the temperature has increased, the ball is no longer flat. How has the average kinetic energy of the air molecules inside the ball changed?
a.It has decreased. b.It has increased
c.It has not changed. d.It has fallen to zero.

19. answer
b.It has increased

20. Question 10
Which of these substances is made up of particles which have the greatest average kinetic energy?
a.cool water b.solid ice
c.warm water d.melting ice

21. answer
c.warm water

22. Question 11 Which of these statements about radiation is true?
a.Particles of a substance must be in contact for radiation to occur.
b.Radiation is the transfer of energy by electromagnetic waves.
c.Radiant energy cannot be reflected by a surface.
d.The thermal energy of a material decreases when it absorbs radiant energy.

23. answer
b.Radiation is the transfer of energy by electromagnetic waves.

24. Question 12
Which of these changes increases the total degree of disorder, or entropy, of the system described?
a.Ice crystals deposit inside a freezer.
b.A liquid boils in a pot on the stove.
c.Liquid drops form on the inside surface of a lid covering a boiling pot of soup.
d.Minerals deposit out of solution from a stream in a cave, creating rock formations.

25. Answer
b.A liquid boils in a pot on the stove.

26. Question 13
The biomolecule adenosine triphosphate, or ATP, stores energy in the bonds that hold it together. When an ATP molecule is broken down, energy is released, which is used in cellular activities like making proteins. When an ATP molecule is broken down, ____.
a.100% of the energy released is available for cellular functions
b.less than 100% of the energy released is available for useful cellular work
c.none of the energy is converted into thermal energy
d.100% of the energy is converted from thermal energy into chemical potential energy

27. Answer
b.less than 100% of the energy released is available for useful cellular work

28. Question 14
Thermal energy is transferred from the Sun to Earth through the process of ____.
a.convection b.radiation
c.conduction d.refraction

29. Answer
b.radiation

30. Question 15
Thermal energy is transferred from a boiling liquid to a metal spoon placed in the liquid through the process of ____.
a.conduction b.refraction
c.convection d.radiation

31. Answer
a.conduction

32. Question 16
Study the description of Erin’s experiment above. If the water in the beaker is heated from 85 degrees Celsius to 100 degrees Celsius, the water molecules ____.
A. do not change their speed
B. will initially move faster, but then move more slowly
C. will move more slowly
D. will move faster

33. Answer
D. will move faster

34. Question 17
Which of these substances is made up of particles which have the least average kinetic energy?
a.ice b.melting ice
c.warm water d.cool water

35. Answer
a.ice

36. Question 18
What two factors must be known to calculate a machine’s efficiency?
a.work input and work output
b.power and work output
c.work input and mechanical advantage
d.power and mechanical advantage

37. Answer
a.work input and work output

38. Question 19
Which of these energy conversions is made possible by the use of geothermal energy?
a.kinetic energy to nuclear energy
b.thermal energy to electrical energy
c.nuclear energy to electrical energy
d.nuclear energy to electromagnetic energy

39. Answer
b.thermal energy to electrical energy

40. Question 20 Date temperature
Oct. 6 20
Oct. 7 18
Oct. 8 14
Oct. 9
Oct. 10 12
Oct. 11 10
Oct. 12 13
Oct. 13
Oct. 14 16
Oct. 15 19
For a period of six days in October, the nighttime temperature in a region falls below 15 degrees Celsius. How does the thermal energy of the molecules of air in this region change during the nighttime hours over this six-day period? a.
Thermal energy decreases. b.
Thermal energy increases. c.
Thermal energy decreases, then increases. d.
Thermal energy does not change.

41. Answer
A. Thermal energy decreases.

42. Question 21
Which of the following substances would make the best insulator? (Hydrogen, Rubber, Aluminum)
Specific Heat of Substances
Hydrogen
Rubber
Aluminum

43. Answer
Hydrogen – has greatest specific heat

44. Question 22
You want to raise the temperature of 0.5kg of Lead from 78 to 83 C. How much heat energy is required to accomplish this?
Specific heat of lead = 130
Q = mcpT

45. Answer
325 J

46. Question 23
If you have a momentum of 908 kg.m/s and a mass of 89kg, how fast are you going?

47. Answer
10.2 m/s

48. Question 24
A 2700 kg car accelerated down the highway from 55 m/s until it reached 72m/s Newtons of force were applied to change the momentum. How long did the force act upon the car?

49. Answer
976.6 seconds

50. Question 25
The cheetah whose mass is 89kg is chasing a gazelle at 19m/s. The gazelle has a momentum of 1699 kg.m/s and a mass of 77kg. Will the gazelle outrun the cheetah? How do you know?

51. answer
Yes, the gazelle has more momentum and speed