Download SPH3U1: DYNAMICS TEST Answer Section

SPH3U1: DYNAMICS TEST
NAME: ______________
Multiple Choice
Identify the choice that best completes the statement or answers the question.
____
1. A curling stone is pushed along the ice surface during its delivery. Which of the following free-body diagrams
best represents the curling stone?
a. A
b. B
c. C
____
2. A hockey puck slides along an ice surface shortly after it has left the hockey stick that propelled it. Which of
the following free-body diagrams best represents the hockey puck?
a. A
b. B
c. C
____
d. D
e. E
3. Study the free-body diagram below and choose the statement that best describes the dynamics of the situation.
a. There is no net horizontal force.
b. The net force acting is 30 N.
c. The net horizontal force is 10 N.
____
d. D
e. E
d. The net force acting is 6 N.
e. The net force acting is 26 N.
4. Study the free-body diagram below and determine what additional force(s) would be required for the object to
achieve uniform motion.
a. 1 N [W]
b. 1 N [E]
c. 2 N [N] and 1 N [W]
d. 2 N [S] and 1 N [E]
e. 2 N [S] and 1 N [W]
____
5. How much force would you have to apply to just support the weight of an average apple of mass 1.0  102 g?
a. 9.8  103 N [up]
d. 9.8  100 N [up]
2
b. 9.8  10 N [up]
e. 9.8  10–1 N [up]
1
c. 9.8  10 N [up]
____
6. A car is travelling with uniform motion with a total frictional resistance of 2.8  103 N acting in a direction
opposite to the motion of the car. What is the force acting on the car in the direction of motion?
a. much greater than 2.8  103 N
d. less than 2.8  103 N
3
b. greater than 2.8  10 N
e. much less than 2.8  103 N
3
c. exactly equal to 2.8  10 N
____
7. A hockey puck of mass 150 g is sliding south along the ice and slows at a rate of 1.2 m/s2. What is the net
force acting on the puck?
a. 1.8  102 N [N]
d. 1.8  10-1 N [N]
b. 1.8  102 N [S]
e. 1.9  10-1 N [S]
1
c. 1.8  10 N [N]
____
8. If the force of gravity that the earth exerts on you is considered to be the action force then, according to
Newton's third law, the corresponding reaction force would be the
a. normal force of the Earth acting upward on you
b. force your feet exert downward on the Earth
c. force of gravity you exert on the Earth
d. force you exert on your feet, pressing them against the Earth
e. force of gravity the Earth exerts on everything else
____
9. If you weighed 112 N on the Moon where g = 1.6 N/kg, how much would you weigh on Earth?
a. 1.1  102 N
d. 1.1  104 N
b. 1.7  104 N
e. 6.9  103 N
2
c. 6.9  10 N
____ 10. What would the gravitational field strength be on a planet with twice Earth's mass and twice its radius?
a. 78.4 N/kg
d. 9.8 N/kg
b. 39.2 N/kg
e. 4.9 N/kg
c. 19.6 N/kg
____ 11. The coefficient of friction stems from the
a. nature of the two surfaces in contact
b. mass of the object
c. strength of the applied force
d. strength of the normal force
e. strength of the gravitational force
____ 12. If the strength of the frictional force is equal to the applied force and oppositely directed, and assuming that
all other forces may be ignored, the object
a. must be at rest
b. must be just about to move
c. may be at rest or moving at uniform velocity
d. must be accelerating
e. must be slowing down
____ 13. Which of the following situations does this free-body diagram represent?
a.
b.
c.
d.
Two students are playing tug-of-war.
An object is in free fall.
A mug sits on a desk.
A student kicks a soccer ball off of the ground.
____ 14. Two ice skaters are standing in the middle of the rink. Skater A has a mass of 65 kg, while skater B has a
mass of 72 kg. Skater A pushes off skater B and accelerates at a rate of 1.6 m/s2. What is the acceleration of
skater B?
a. 1.3 m/s2
b. 1.6 m/s2
c. 1.4 m/s2
d. 1.7 m/s2
Completion
Complete each statement.
15. The property of matter that resists a change in an object's motion is called ____________________.
16. According to Newton's second law, the acceleration of an object is directly proportional to the
____________________ and inversely proportional to the ____________________.
17. Imagine you're standing on a bathroom scale inside an elevator. The scale will read your normal weight when
the elevator is ____________________ or when the elevator is _________________________.
18. A 2500-kg elevator is moving vertically upward with a constant speed of 2.0 m/s. The value of the net force
acting on the elevator is ____________________.
19. A newspaper article described an accident by stating that “the rider was thrown from his motorcycle when it
hit a parked car”. According to Newton’s First Law, what is wrong with the wording of this statement?
PROBLEMS
20. One of the top drag racers in the world is able to reach speeds of 530 km/h over a distance of 400.0 m.
Calculate the net force acting on the car if the mass of a drag racer is 850 kg. (4)
21. During a nordic ski race, Kaylee pushes with both poles producing a combined horizontal force of 345 N. If
Kaylee and her equipment have a mass of 55.0 kg and the coefficient of kinetic friction between her skis and
the snow is 0.25, what acceleration will she experience during the push? (4)
22. An object of mass 40.0 kg rests on the surface of a planet with a mass of 8.2  1022 kg and radius 3.6 105 m.
A) Calculate the force of gravity acting on the object. (2)
B) Calculate the gravitational field strength. (1)
23. A ride at an amusement park accelerates riders vertically upwards using a bungee cord. At a particular instant
of time a 75 kg rider is accelerating upwards at a rate of 20.0 m/s2. (5)
a) Draw a free body diagram.
b) What would the force of tension in the cord be at that moment?
24. Three sleds are tied together and pulled with a force of 150 N [E]. The mass of sled 1 is 13.0 kg, the mass of
sled 2 is 10.0 kg, and the mass of sled 3 is 8.0 kg. Assume that the force of friction is negligible. What is the
tension in rope B? (3)
SPH3U1: DYNAMICS TEST
Answer Section
MULTIPLE CHOICE
1. ANS:
STA:
2. ANS:
STA:
3. ANS:
STA:
4. ANS:
STA:
5. ANS:
STA:
6. ANS:
STA:
7. ANS:
STA:
8. ANS:
STA:
9. ANS:
STA:
10. ANS:
STA:
11. ANS:
STA:
12. ANS:
STA:
13. ANS:
LOC:
14. ANS:
LOC:
E
FM2.04
D
FM2.04
D
FM2.04
E
FM2.04
E
FM1.05
C
FM1.08
D
FM1.08
C
FM1.07
C
FM1.05
E
FM1.05
A
FM1.01
C
FM1.07
D
C2.2
C
B2.4
PTS: 1
REF: I
OBJ: 2.2
PTS: 1
REF: I
OBJ: 2.2
PTS: 1
REF: I
OBJ: 2.4
PTS: 1
REF: I
OBJ: 2.2
PTS: 1
REF: K/U
OBJ: 2.2
PTS: 1
REF: K/U
OBJ: 2.2
PTS: 1
REF: K/U
OBJ: 2.4
PTS: 1
REF: K/U
OBJ: 2.5
PTS: 1
REF: K/U
OBJ: 3.2
PTS: 1
REF: K/U
OBJ: 3.2
PTS: 1
REF: K/U
OBJ: 3.3
PTS: 1
REF: K/U
OBJ: 3.3
PTS:
MSC:
PTS:
MSC:
1
REF: C
Analysis and Application
1
REF: T/I
Analysis and Application
OBJ: 3.1 Types of Forces
OBJ: 3.4 Newton's Third Law of Motion
COMPLETION
15. ANS: inertia
PTS: 1
REF: K/U
16. ANS: net force, object's mass
OBJ: 2.2
STA: FM1.01
PTS: 1
REF: K/U
OBJ: 2.4
17. ANS: motionless, undergoing uniform motion
STA: FM1.08
PTS: 1
18. ANS: zero
PTS: 1
REF: K/U
OBJ: 2.4
STA: FM1.07
REF: K/U
OBJ: 2.2
STA: FM1.05
19. ANS: ;j
PTS: 1
SHORT ANSWER
20. ANS:
Given: = 530 km/h;
Required: Fnet
= 0 km/h;
= 400.0 m; m = 850 kg
Analysis: First, convert the velocity to SI units. Then calculate the acceleration using
Calculate the average applied force using
Solution:
.
Statement: The average force applied by the engine is 23 000 N.
PTS: 1
LOC: C2.3
PROBLEM
21. ANS:
REF: T/I
OBJ: 3.3 Newton's Second Law of Motion
MSC: Analysis and Application
.
The object will accelerate at a rate of 4  10–1 m/s2 [N].
PTS: 1
22. ANS:
REF: I
OBJ: 3.4
(a)
The force of gravity acting is 1.7  103 N.
(b)
The gravitational field strength is 42 N/kg [down].
STA: FM2.04
(c)
The force of gravity acting is 2.2  102 N.
PTS: 1
23. ANS:
D
PTS: 1
24. ANS:
S
PTS: 1
REF: I
OBJ: 3.2
STA: FM2.04