Download Fall 2016 EOS Review Key

Name:_______________
Period:________
Physics EOS Review Fall 2016
THE CORRECT ANSWERS IN BOLD
Consider the conventional graph of position vs. time shown.
1. Position is negative and velocity is positive at which point?
A.) A
C.) C
E. )E
G.) G
B. )B
D.) D
F. )F
H. )H
2. At point E,
A. position is positive and velocity is positive
B. position is positive and velocity is zero
C. position is positive and velocity is negative
D. position is zero and velocity is positive
E. position is zero and velocity is negative
F. position is negative and velocity is positive
G. position is negative and velocity is zero
H. position is negative and velocity is negative
Consider the conventional graph of velocity vs. time shown.
3. At 3 s, the object is
A. traveling in the positive direction
B. traveling in the negative direction
C. traveling in either the positive or negative direction
D. at rest
4. Which of the following involve a change in velocity?
A. A change in speed
B. A change in direction of motion
C. Both of these
D. None of these
5. A ball is thrown straight up. At the highest point in its flight, the speed of the ball is most nearly
A. 0 m/s B. 1 m/s C. 10 m/s D. 100 m/s E. 1000 m/s
6. A ball is thrown straight up. At the highest point in its flight, the magnitude of acceleration of the ball is most
nearly
A. 0 m/s2 B. 1 m/s2 C. 10 m/s2 D. 100 m/s2 E. 1000 m/s2
7. How far does an object travel if its speed is 8 m/s and it travels for 2 s?
A. 0.25 m B. 0.5 m C. 2 m D. 4 m E. 16 m F. 32 m
8. A pitcher takes 0.1 s to accelerate a baseball from rest to 30 m/s. The ball's acceleration is
A. 3 m/s2
B. 30 m/s2
C. 300 m/s2 D. 3000 m/s2
9. A car starts from a speed of 10 m/s with an acceleration of 2 m/s2. The time needed for the car to reach 20
m/s is
A. 5 s B. 10 s C. 15 s D. 20 s
E. 30 s
10. A brick is dropped from a high scaffold.
a. What is its velocity after 4.0 s? 39.2 s
b. How far does the brick fall during this time? 78.4m
11. A tennis ball is thrown straight up with an initial speed of 22.5 m/s. It is caught at the same
distance above the ground.
a. How high does the ball rise? 25.8 m
b. How long does the ball remain in the air? 4.6s
12. Consider the following velocity-time graph.
Determine the displacement after t = ...
a. 10 s.
(40m) b. 20 s. (130m)
c. 30 s.
(230m)
d. 40 s.
(265m)
13. A bag is dropped for a hovering helicopter. When the bag has fallen for 2.00 s,
a. What is the bag’s velocity? 19.6 m/s
b. How far has the bag fallen? 19.6 m
14. Speed is _____.
(A) a measure of how fast something is moving.
(B) the distance covered per unit time
(C) always measured in terms of a unit of distance divided by a unit of time
(D) all of the above
(E) none of the above
15. What is the SI Unit of velocity? ____m/s______
16. When you look at the speedometer in a moving car, you can see the car’s _____.
(A) instantaneous speed.
(B) average speed
(C) average acceleration
(D) instantaneous acceleration
(E) average distance traveled
17. Acceleration is defined as the rate of change of _____.
(A) distance
(B) velocity
(C) time it takes to move from one speed to another speed
(D) time it takes to move from one place to another place
(E) displacement
18. Suppose you are in a car that is going around a curve. The speedometer reads a constant 30 miles per hour.
Which of the following is NOT true?
(A) You and the car are accelerating.
(B) Your speed is constant.
(C) Your velocity is constant.
(D) Your direction is constantly changing.
19. An object travels 3 m in the first second of travel, 3 m again during the 2nd second of travel, and 3 m again
during the third second of travel. Its acceleration is _____.
(A) 0 m/s2
(B) 8 m/s2
(C) 16 m/s2
(D) 32 m/s2
(E) none of the above
20. Ten seconds after starting from rest, a car is moving at 40 m/s. What is the car’s acceleration? A= Vf-Vi
(A) 0.25 m/s2
(B) 2.5 m/s2
(C) 4.0 m/s2
(D) 10 m/s2
(E) 40 m/s2
21. What is the physical meaning of the slope of a Velocity vs. Time graph?
(A) Distance
(B) Position
(C) Acceleration
(D) m/s
22. In the absence of air resistance, objects fall at constant ____.
(A) velocity
(B) speed
(C) acceleration
(E) none
(D) distances each successive time interval
23. A ball is thrown upwards and caught when it comes back down. In the absence of air resistance, the speed
of the ball when caught would be
(A) more than the speed it had when thrown upwards
(B) less than the speed it had when thrown upwards
(C) the same as the speed it had when thrown upwards
24. Suppose an object is in free fall. Each second the object falls _____.
(A) with the same average speed
(B) with the same instantaneous speed
(C) the same distance as in the second before
(D) a larger distance than in the second before
(E) none of the above
25. If a swimmer has to swim 5 laps of the pool (to the end and back), with one length of the pool being 50
meters, what is the swimmer’s displacement?
(A) 250m
(B) 500m
(C) 0m
(D) 2m
26. A ball tossed vertically upward rises, reaches its highest point, and then falls back to its starting point.
During this time, the acceleration of the ball is always _____.
(A) in the direction of motion
(B) opposite its velocity
(C) directed upward
(D) directed downward
27. When the ball reaches its highest point, its speed is _____.
(A) 0 m/s
(B) about 5 m/s
(C) about 10 m/s (D) about 20 m/s
28. When the ball reaches its highest point, the magnitude of its acceleration is _____.
(A) 0 m/s2
(B) about 5 m/s2
(C) about 10 m/s2
(D) about 20 m/s2
29. 8. What is the physical meaning of the slope of a Position vs. Time graph?
(A) Distance
(B) Velocity
(C) Acceleration (D) m/s
(E) none
True or False:
30. The rate at which distance is covered is called speed._ _____True_____
31. Average speed is defined as the time it takes for a trip divided by the distance traveled. _False v=d/t_______
32. Velocity is different from speed in that velocity is speed in a given direction. ____True_______
33. The SI unit of velocity is the meter. _____False m/s______
34. The rate at which velocity changes with time is called acceleration. _______True____
35. The SI unit of acceleration is m/s. ____False m/s2_______
36. When a car rounds a corner at constant speed, its acceleration is zero. _True_ direction is changing___
37. Even though a car is slowing down, it is still accelerating. ________True___
38. A ball is thrown into the air. At the highest point, the ball has zero velocity and zero acceleration.
___False____
39. As a ball falls freely, the distance it falls each second is the same. _______False____
Problems. GUESS method required! (USE -9.8 m/s2 for acceleration due to gravity)
40. What is the average speed of a cheetah that runs 65 m in 3.0 seconds?
V= d/t 65m / 3sec= 21.67 m/s
41. What is the acceleration of a car that was traveling at 30 m/s and hit brakes to come to a stop in 1.7 s ?
a= Vf-Vi
0m/s-30m/s
a=-17.647 m’s2
t
1.7 s
42. What is the acceleration of a car that goes from rest to 59 m/s in 9.0 seconds?
a= Vf-Vi
t
59 m/s- 0 m/s
a=6.56 m/s2
9s
43. How much time does a car with an acceleration of 4.0 m/s2 take to go from 10.0 m/s to 30.0 m/s?
4 m/s2 = 30 m/s – 10 m/s
t= 5 sec
t
44. In the previous problem how far did the car travel?
Vi= 10 m/s
a= 4 m/s2
Vf= 30 m/s d= ½ (Vi + Vf) t
d = ½ (10 m/s + 30 m/s) (5 sec)
d = 100 m
45. An apple drops from a tree and 0.5 seconds later hits the ground. What is its velocity when it hits the
ground?
a = 9.81 m/s2
t = 0.5 sec
Vi= 0 m/s Vf = ?
Vf = Vi + a (t)
Vf = 4.905 m/s
46. How far did that apple fall?
d = ½ (Vi +Vf) t
d = ½ (0 m/s + 4.905 m/s) 0.5 s
d= 1.22625
47. Starting from rest, a car undergoes a constant acceleration of 6.0 m/s2. How far will the car travel in the 17
seconds of travel?
Vi= 0 m/s a= 6.0 m/s2 t= 17 sec d = ? d= Vi x t + (1/2 a t2) d= 867 m
48. A stone is dropped from a cliff. After it has fallen 35 sec, what is the stone’s velocity?
Vi = 0 m/s a= 9.81 m/s2 t= 35 sec Vf=? Vf= Vi + a(t)
Vf= 343.35 m/s
49. What is the value for the universal gravitational constant G (include units)_____Nm2/kg2_________
50. How are the force of gravity and mass related?
A. Direct
B) Inverse
C) Inverse square D) Not related at all
51. How are the force of gravity and distance related?
A) Direct
B) Inverse
C) Inverse square
D) Not related at all
52.What happens to the force of gravity if the one mass is doubled?
A) It doubles
B) It quadruples
D) It is ¼ the original value
E) It is constant
C) It is half the original value
53.What happens to the gravitational force if both masses are doubled?
A) It doubles
B) It quadruples
D) It is ¼ the original value
E) It is constant
C) It is half orig. value
54.What happens to the force of gravity if the distance between the objects is reduced by half?
A) It doubles
B) It quadruples C) It is half the original value
D) It is ¼ the original value
E) It is constant
55.What happens to the gravitational force if the distance between the objects is doubled?
A) It doubles
B) It quadruples
C) It is half the original value
D) It is ¼ the original value E) It is constant
56.What happens to the force of gravity if both masses are doubled and the distance between the objects is
doubled?
A) It doubles
B) It quadruples
C) It is half the original value
D) It is ¼ the original value
E) It is constant
57. A stone on the edge of the tire of a unicycle wheel with a radius of 0.25 m has a centripetal acceleration of
4.0 m/s2. What is the tire's tangential (or linear) speed? (DRAW A PICTURE AND USE GUESS
METHOD TO SOLVE)
A) 4.0 m/s
B) 16 m/s
C) 0.063 m/s
D) 1.0 m/s
Given: R = .25 m
Ac = 4.0 m/s2
Unknowns:
Vt (tangential speed)
Equation: AC = (Vt)2 / R rearranged (Vt) = Ac(R)
Substitute (Vt)2 = (4.0 m/s2) (.25 m)
Solve
Vt = 1.0 m/s
58. If the distance from the center of a merry-go-round to the edge is 1.2 m, what centripetal acceleration does
a passenger experience when the merry-go-round rotates at a speed of 1.5 m/s? (DRAW A PICTURE AND USE
GUESS METHOD TO SOLVE)
A) 1.7 m/s2
B) 1.9 m/s2
C) 0.9 m/s2
D) 0.6 m/s2
Given: R = 1.2 m
Vt = 1.5 m/s
Unknowns:
Ac centripetal acceleration
Equation: AC = (Vt)2 / R
Substitute Ac = (1.5 m/s)2 / (1.2 m)
Solve
Ac = 1.9 m/s2
59. A 80.0 kg passenger is seated 12 m from the center of the loop of a roller coaster. What centripetal force
does the passenger experience when the roller coaster reaches an tangential speed of 38m/s? (DRAW
A PICTURE AND USE GUESS METHOD TO SOLVE)
A) 1.7 x 103 N
B) 7.2 x 103 N
3
C) 6.9 x 10 N
D) 9.6 x 103 N
Given: R = 1.2 m
Vt = 38 m/s
M = 800 kg
Unknowns:
Fc centripetal force
must find Ac centripetal acceleration first
Equation: AC = (Vt)2 / R
F = M Ac
Substitute: Ac = (38 m/s)2 / (12 m)
F = (80.0 kg)(120.3m/s2)
Solve:
Ac = 120.3 m/s2
F = 9.6 x 103 N
60. A 0.40 kg ball on a 0.50 m string rotates in a circular path in a vertical plane. If the tangential speed of the
ball at the bottom of the circle is 4.0 m/s, what is the centripetal force that maintains circular motion? (DRAW A
PICTURE AND USE GUESS METHOD TO SOLVE)
A) 5.6 N
B) 13 N
C) 11 N
D) 20.0 N
Given: R = .5 m
Vt = 4.0 m/s
M = .40 kg
Unknowns:
Fc centripetal force
must find Ac centripetal acceleration first
Equation: AC = (Vt)2 / R
F = M Ac
Substitute: Ac = (4.0 m/s)2 / (.50 m)
F = (.40 kg)(32 m/s2)
Solve:
Ac = 32 m/s2
F = 13 N
61. The force applied in order to maintain the circular motion is called
A) centrifugal force
B) tangential force
C) centripetal force
D) gravitation force
62. The linear velocity of an object directed along the tangent of an object’s circular path is called
A) centripetal velocity
B) tangential velocity
C) centripetal force
D) tangential force
63. Explain the difference between rotation and revolution.
Rotation – an object spins around an INTERNAL axis (example: day)
Revolution – object spins around an EXTERNAL axis (example: year)
64. What is the difference between centripetal force and centrifugal force?
term use for forces in circular motion?
Which of these terms is correct
Centrifugal Force – a force that pushes you away from the center
Centripetal Force -- a force coming from the center of the path that is directed on you
WE ONLY TALK ABOUT CENTRIPETAL FORCE !!!!!!!!!!!!!!!
65. For this small solid object swinging in a circle in the direction shown, draw and label the vectors for
centripetal force, centripetal acceleration and tangential velocity.
Fc
Ac
Vt
66. What is the gravitational force between a lion (250 kg) and a gazelle (100 kg) that are separated by distance
of 60 meters? (DRAW A PICTURE AND USE GUESS METHOD TO SOLVE)
Givens: M1 = 250 kg M2 = 100 kg R = 60 m G = 6.673 x 10-11 N m2 / kg2 (Gravitational Constant)
Unknown: Fg Gravitation Force
Equation: Fg = G (M1)(M2) / R2
Substitute: Fg = (6.673 x 10-11 N m2 / kg2)(250 kg)(100 kg)/(60 m)2
Solve:
Fg = 4.63 x 10-10 N
67. If the distance between the lion and gazelle is 30 meters, what is the new gravitational force?
Write a statement explaining the relationship between gravitational force and distance.
Givens: M1 = 250 kg M2 = 100 kg R = 30 m
Unknown: Fg Gravitation Force
G = 6.673 x 10-11 N m2 / kg2 (Gravitational Constant)
Equation: Fg = G (M1)(M2) / R2
Substitute: Fg = (6.673 x 10-11 N m2 / kg2)(250 kg)(100 kg)/(30 m)2
Solve:
Fg = 1.85 x 10-9 N
******** NOTICE: The distance was reduce by ½, so the gravitational force quadrupled.******
Two students are riding a roller coaster at Six Flags. Their 3,000 kg car moves with a speed of 24.0 m/s
through a curve which has a radius of 20.0 meters. (DRAW A PICTURE AND USE GUESS METHOD TO
SOLVE)
68. What is their centripetal acceleration at this point?
Given: R = 20.0 m
Vt = 24.0 m/s
M = 3,000 kg
Unknowns:
Ac centripetal acceleration
Equation: AC = (Vt)2 / R
Substitute: Ac = (24.0 m/s)2 / (20.0 m)
Solve:
Ac = 28.8 m/s2
69. What is the centripetal force exerted on the vehicle by the track?
Given: M= 3,000 kg
Ac = 28.8 m/s2 (found in problem above)
Unknowns:
Fc centripetal force
Equation: FC = M (Ac)
Substitute: Fc = (3,000 kg) (28.8. m/s2)
Solve:
Fc = 86,400 N
70. An airplane is flying in a horizontal circle at a speed of 105 m/s. The pilot’s mass is 80.0 kg. (g = 9.81 m/s 2)
(DRAW A PICTURE AND USE GUESS METHOD TO SOLVE)
If the pilot does not want the centripetal acceleration to exceed 5,000 m/s 2, what is the minimum radius of the
plane’s path?
Given: Vt = 105 m/s Ac = 5000 m/s2 M = 80 kg
Unknowns:
Radius (R)
Equation: AC = (Vt)2 / R rearranged R = (Vt)2 / Ac
Substitute: R = (105 m/s)2 / (5000 m/s2)
Solve:
R = 2.2 m
71. At this radius, what is the magnitude of the centripetal force that acts on the pilot?
Given: Vt = 105 m/s Ac = 5000 m/s2 M = 80 kg
(Gravity is not needed since this a horizontal problem)
Unknowns:
Fc centripetal force
Equation: FC = M (Ac)
Substitute: Fc = (80 kg) (5000 m/s2)
Solve:
Fc = 40,000 N
72. If the radius the doubled, what happens to the centripetal acceleration?
A) It doubles.
B) It quadruples.
C) It is reduced to ½
D) It stays constant.
73. If the tangential velocity is doubled what happens to the centripetal acceleration?
A) It doubles.
B) It quadruples. C) It is reduced to ½
D) It stays constant.
74. If the centripetal acceleration doubles, what happens to the centripetal force?
A) It doubles.
B) It quadruples.
C) It is reduced to ½
D) It stays constant.
75. Centripetal force is ___________________________.
A) directed towards the center
C) both A and B
B) directed away from the center
D) neither A nor B
76. Newton’s First Law states that an object _____.
a. at rest will remain at rest unless acted on by an outside force
b. will continue moving at the same velocity unless acted on by an outside force
c. will continue moving in a straight line unless acted on by an outside force
d. that is not moving will never move unless a force acts on it
e. all of the above
77. The law of inertia applies to _____.
a. moving objects b. objects at rest c. both moving and nonmoving objects
78. After a cannon ball is fired into frictionless space, the amount of forced needed to keep it going equals _____.
a. twice the force with which it was fired
b. the same amount of force with which it was fired
c. on half the force with which it was fired
d. one quarter the force with which it was fired
e. zero, since no force is necessary to keep it moving
79. A sheet of paper can be withdrawn from under a container of milk without toppling it if the paper is jerked
away quickly. The reason this can be done is that _____.
a. the milk carton has very little weight
b. there is an action-reaction pair operating
c. gravity pulls very hard on the milk carton
d. the milk carton has inertia
e. none of the above
80. One object has twice as much mass as another object. The first object also has twice as much _____.
a. inertia
b. velocity
c. gravitational acceleration
d. energy e. all of the above
81. Compared to its weight on earth, a 50 kg object on the moon will weigh _____.
a. less
b. more
c. the same amount
82. The mass of a dog that weighs 100 N is about _____.
a. 1 kg
b. 10 kg c. 100 kgd. 1000 kg
e. none of the above
83. An object following a straight line path at constant speed _____.
a. has a net force acting on it in the direction of motion
b. has zero acceleration
c. must be moving in a vacuum
d. has no forces acting on it
e. none of the above
84. Friction _____.
a. acts in a direction that opposes the motion of an object
b. comes from microscopic bumps that act as obstructions to the objects motion
c. is the name given to the force acting between surfaces sliding past one another
d. all of the above
e. none of the above
85. A 10 N force west and a 30 N force east act on an object concurrently. What is the net force acting on the
object?
a. 40 N east
b. 30 N west
c. 20 N east
d. 20 N west
e. none of the above
86. You would have the largest mass of gold if your chunk of gold weighed 1 N on _____.
a. the moon
b. Earth
c. it doesn’t matter which planet you are on.
87. Which are true at equilibrium?
a. all the forces acting on an object are balanced
b. the sum of the forces acting rightward equal the sum of the forces acting leftward.
c. the sum of the forces acting upward equal the sum of the forces acting downward.
d. the net force is zero.
e. all of the above.
88. With a constant force, how does the acceleration of an object change in relation to its mass?
a. directly proportional
b. inversely proportional
c. acceleration doesn’t depend on mass at all
89. The acceleration produced by a net force on an object is _____.
a. directly proportional the magnitude of the net force.
b. in the same direction as the net force
c. inversely proportional to the mass of the object
d. all of the above
e. none of the above
90. A girls pulls a 10 kg wagon with a net force of 30 N. What is the wagon’s acceleration?
a. 0.3 m/s2
b. 3.0 m/s2
c. 10 m/s2
d. 30 m/s2
e. 300 m/s2
It is _____.
91. A force of 1N accelerates a mass of 1 kg at the rate of 1 m/s2. The acceleration of a mass of 2 kg acted upon
by a force of 2 N is _____.
a. half as much
b. twice as much c. the same
d. none of the above
92. A block is dragged without acceleration in a straight line path across a level surface by a force of 6 N. What
is the frictional force between the block and the surface?
a. less than 6 N
b. more than 6 N
c. 6 N
d. need more information t
93. A person weighs 500 N. What is the mass of the person?
W = mg
so m = 500N/10m/s2
m = 50kg
94. A 200 kg bear grasping a vertical tree slides down at a constant velocity. What is the friction force between
the tree and the bear? Draw a FBD.
F = Wt = 200kg(9.8 m/s2) = 1960N
95. A certain unbalanced force gives a 5 kg object an acceleration of 2.0 m/s2. What acceleration would the
same force give a 30 kg object?
F = (5kg)(2m/s2) = 10N
10N = 3kg (a)
a = 1/3 m/s2