Exam 1 applied physics

1)"Physics" could best be described as the study of

B) the general principles underlying natural phenomena.

2)A primary reason for you to learn science, according to the textbook's opening section, is

C)to increase your awareness.

3)Our primary reason for studying the theories of Ptolemy, Copernicus, and Kepler in this course is

C)to learn about the methods and the validity of science.

4)If you observe the night sky in the direction of the North Star, you will observe that

D)the other stars near the north star move along counterclockwise circles around the north starduring the night.

5)In Ptolemy's theory,

E)the planets move in circles-within-circles \["loop-the-loops"\] around Earth.

6)The ancient Greeks, including Ptolemy, thought that the stars were

A)fixed to the inside surface of a large sphere that enclosed the universe.

7)The very earliest Greek cosmological theory, several centuries before Ptolemy, stated that

C)the planets go in simple circles around Earth.

8)The Greeks abandoned their earliest cosmological theory (planets moving in simple circles aroundEarth) because

A)it did not agree with their observations of the planets.

9)The greatest astronomer of antiquity \[that is, of the time before the Middle Ages\] was

B)Ptolemy.

10)The ancient Greeks noted that the planets

C)wandered around among the stars.

11)One ancient Greek scientist, Aristarchus, had a theory about the layout of the universe that wasquite different from the other Greek theories. According to Aristarchus's theory,

C)the sun is at the center and other objects, including Earth, move around the sun in simplecircles.

12)How did ancient Greeks such as Aristotle know that Earth is round?

C)By noting that ships drop below the horizon as they go out to sea.

13)Venus is usually either the "evening star" or the "morning star" because

D)its orbit around the sun is inside Earth's orbit.

14)Copernicus proposed his theory because

B)he thought that Ptolemy's theory was too messy and that his was more "fitting."

15)The most significant difference between the astronomical theories of Ptolemy and Copernicus is

C)Ptolemy's theory is sun-centered, whereas Copernicus's is Earth-centered.

16)In Ptolemy's theory, retrograde planetary motion is explained as

B)the backward part of the planet's loop-the-loop orbits around Earth.

17)Who originated the idea that planets go inellipses around the sun?

D)Kepler

18)A scientific theory \[or scientific principle\] could best be described as

A)an idea that explains a large collection of observations of the natural world.

19)Is it possible to prove, for certain, that a scientific theory is true?

E)No, because it is always possible that a future experiment will disagree with the theory.

20)How is the sun situated in the universe?

E)The sun is just one of a large number of stars, and is located on the fringes of the Milky Waygalaxy, which itself is just one galaxy among many galaxies.

21)A defining feature of "pseudoscience" is

A)it does not use proper scientific methodology.

22)The "father" of atomic materialism was

A)Democritus.

23)Roughly how many different elements are there?

A)100

24)The number of atoms in the glucose molecule, C6H12O6, is

B)24.

25)How many atoms are in the alcohol molecule C2H5OH?

A)9

26)The number of atoms in the sulfuric acid molecule, H2SO4, is

C)7.

27)Chemically, helium is

D)an element.

28)The distance to the sun is about 150 million km. Expressed in powers of ten, this is

A)1.5× 108 km.

29)Which is smallest?

B)the sun

30)According to the philosophy of Democritus,

A)the color red is not "real" but is instead just humans' "conjecture" or imagination.

31)Democritus said that, although we imagine many things, "in reality, there are only atoms and thevoid." This idea could best be classified as

D)materialism.

32)According toAristotle, which of these is a "natural" or "unforced" motion?

C)Both of the above.

33)A book is given a brief shove along a table top and released so that it slides a short distance andcomes to rest.Galileo would say that the book stopped because

B)of friction.

34)A stone is lifted and released so that it falls to the ground. According toAristotle, it fell because

B)its natural motion is to fall.

35)A stone is lifted and released so that it falls to the ground. According toGalileo, it fell because

E)of gravity.

36)What, if any, evidence did Galileo have for the law of inertia?

A)A smooth ball slows down when rolling uphill, and speeds up when rolling downhill, so itshould maintain an unchanging speed on a level surface.

37)According to Newtonian physics, an object with no forces acting on it must

E)either be at rest or have constant velocity.

In the figure, the moon is moving clockwise in a circular orbit around Earth. Imagine that gravitywas suddenly shut off, throughout the solar system, at the instant when the moon is in the positionshown in the figure. How would the moon move, after gravity was shut off?

A)In the direction of arrow B, in a straight line.

39)A ball is moving at 20 m/s. If no forces act on it, then 5 seconds later the ball's speed will be

C)20 m/s.

40)You ride a motor scooter 8 km in 15 minutes. Your \[average\] speed is

A)32 km/hr.

41)Mary passes Mike from behind while bicycling. As she passes him,

B)the two have different speeds and different velocities

The figure represents a multiple-flash photo of two balls moving to the right, and shows both ballsat several numbered times. The time between flashes is 0.20 s, and thelarge divisions on themeasuring rod are centimeters. The speed of the lower ball is

D)6 cm/s.

43)It is 6 km to Centerville, and you bicycle there in 20 minutes. Your speed is

D)18 km/hr.

44)Is it possible for an object to accelerate but without changing its speed?

B)Yes, for example when a car turns a corner while maintaining an unchanging speed.

45)Edgar Jones, angry at having purchased a tasteless pizza, drops his pizza off the Brooklyn bridge.As it falls, Edgar's pizza has a constant \[or unchanging\]

A)acceleration.

46)An object is dropped from rest on the planet Jupiter. At the end of 1 second, it has fallen 8 m and ismoving at 16 m/s. What was its average speed during the entire first second \[i.e., from t=0 until t=1sec\]?

A)8 m/s

47)Suppose you are on the moon and you drop a rock and a feather at the same time. You will findthat

B)the two fall at the same speed, but this speed is slower than a rock would fall on Earth.

48)On the planet Venus, a Venusian picks up a stone and drops it into a deep hole. If it falls 3 m in 1second, how far will it fall in 2 seconds? You can neglect Venusian air resistance.

B)12 m

49)Galileo's principle of falling is limited by the condition that

A)air resistance must be negligible.

50)A rock is dropped from rest off of a high cliff on another planet, planet X. There is no atmosphere,and thus no air resistance, on planet X. At the end of 1 second, the rock is moving at a speed of 6m/s. At the end of 2 seconds, it is moving at 12 m/s. How fast will the rock be moving at 4 secondsafter being dropped?

A)24 m/s

51)The accelerationdue to gravity is 10 m/sec2. If an object falls from rest, its instantaneous speed atthe end of the fifth second is (neglecting air resistance)

D)50 m/sec.

52)Which of the following best describes the meaning of "force"?

D)A body exerts a force on another body when the first body causes the second body toaccelerate.

53)Object A has twice as much mass as object B. If you exert the same force on these two objects, howdo their accelerations compare?

A)Object A has half as much acceleration as object B.

54)Regarding the relation between acceleration, force, and mass, an object's acceleration is

E)proportional to the force on it and inversely proportional to the object's mass.

55)Which of the following is the basic \[and most accurate\] meaning of "mass"? An object's "mass" is

D)the amount of inertia it contains.

56)The main point of Newton's law of motion is that forces cause

A)acceleration.

57)You push your 2 kg physics book along a tabletop, pushing it with 10 newtons of force. If the bookis greased so that friction is negligible, the book's acceleration is

D)5 m/s2.

58)You push your 2 kg physics book along a tabletop, pushing it with 10 newtons of force. Thefrictional force on it is 4 newtons. The book's acceleration is

E)3 m/s2.

59)A girl lifts a ball by means of a string attached to the ball. The string exerts a 20 newton force on theball. The ball weighs 8 newtons. The net force on the ball is

D)12 newtons.

60)A girl lifts a ball by means of a string attached to the ball. The string exerts a 30 newton force on theball. The ball weighs 20 newtons and has a mass of 2 kilograms. The acceleration of the ball is

B)5 m/s2.

61)Forces of 8 N and 3 N act on an object. If the two forces act in opposite directions, the net force onthe object is

B)5 N.

62)The law of inertia says that

E)if there is no force on a body, the body will have no acceleration.

63)A rocket taking off straight upward develops a thrust of 10,000 newtons. The rocket weighs 2,000newtons. Thenet force on the rocket, neglecting air resistance, is

E)8,000 newtons.

64)You would be richest if your hunk of gold had amass of one kilogram

C)Actually it wouldn't make any difference.

65)You would be richest if your hunk of goldweighed 10 newtons

A)on the moon.

66)Would you be richer if you had a hunk of gold whose weight is 1 newton on the moon, or onewhose weight is 1 newton on Earth, and why?

B)1 newton on the moon, because then the gold's mass would be larger.

Mary pushes horizontally on a large, heavy table, which is standing alone in the middle of a room,and notes that the table does not move despite the fact that she is pushing on it (see the figure). Whydoesn't the table move?

D)Frictional forces by the floor on the table legs acted in the opposite direction to produce a netforce of zero.

68)An auto travels down a straight, level road at constant speed. One force that acts on the auto is

A)the road pushing upward on the auto.

69)An object's "momentum" is defined as

B)its mass times its velocity.

70)A stationary firecracker explodes, breaking into two parts of equal mass. One part is moving northat 20 m/s. The velocity of the other part is

A)southward at 20 m/s.

71)Which of the following principles explains why guns recoil?

A)Conservation of momentum.

72)A pool ball moving at 3 m/s collides head-on with an identical pool ball that's initially at rest. Justafter the collision, the second ball moves away at 2 m/s while the first ball

E)moves at 1 m/s in the same direction as the second ball.

73)A 39-kg girl standing at rest on slippery (frictionless) ice catches a 1-g ball moving at 10 m/s. Justafterward, the girl is

The right answer

74)A hypothesis is

A)an unconfirmed suggestion

75)A theory is

A)a well confirmed framework of ideas that explains what we observe.