UNIT
1
Self-qUIz
K/U
Knowledge/Understanding
For each question, select the best answer from the four
alternatives.
1. The position–time graph shown in Figure 1 depicts
which of the following situations? (1.1) K/U
d
Position v. Time
t
Figure 1
(a) positive velocity, positive acceleration, negative
acceleration
(b) zero velocity, negative acceleration, positive
acceleration
(c) zero velocity, positive acceleration, negative
acceleration
(d) negative velocity, zero acceleration, positive
motion
2. An ice hockey player set a record speed for a slap shot:
177.58 km/h. Suppose the hockey player accelerated
the hockey puck through a distance of 1.25 m. What
was the magnitude of the acceleration? (1.2) K/U T/I A
(a) 19.7 m/s2
(b) 71.0 m/s2
(c) 973 m/s2
(d) 1260 m/s2
3. A ship sails 150.0 km [E 608 N] into Hudson Bay
from Fort Severn. The ship then changes course and
travels 350.0 km [N]. What is the total displacement
of the ship? (1.3) K/U T/I A
>
(a) Dd T 5 485.7 km [E 81.128 N]
>
(b) Dd T 5 485.7 km [E 8.7128 N]
>
(c) Dd T 5 444.4 km [E 73.008 N]
>
(d) Dd T 5 444.4 km [E 17.018 N]
4. To cross a river with a current in the least amount of
time, how should a boat point? (1.3) K/U T/I A
(a) somewhat downstream
(b) somewhat upstream
(c) directly at the opposite shore
(d) in a direction that will take the boat directly
across
148
Unit 1 • Dynamics
8160_CH03_p135-157.indd 148
T/I
Thinking/Investigation
C
Communication
A
Application
5. A helicopter moves in an arc so that its velocity
changes from 77 km/h [S] to 77 km/h [E] in 15 s.
What is the acceleration of the helicopter?
(1.4) K/U T/I A
(a) 1.4 m/s2 [W 458 S]
(b) 2.0 m/s2 [E 458 N]
(c) 5.1 m/s2 [E 458 S]
(d) 5.1 m/s2 [E 458 N]
6. A ball kicked with a speed of 12.0 m/s at an angle
of u above the horizontal lands at a distance of
14.47 m away from the kicker. The total vertical
displacement of the ball is zero. What is the value
of u? (1.5) K/U T/I A
(a) 30.08
(b) 35.08
(c) 40.08
(d) 45.08
7. A ship travelling at 39.0 km/h [N] across the
St. Lawrence Seaway encounters a current of
13.0 km/h [E 50.08 N]. What is the velocity of the
ship with respect to the shore? (1.6) K/U T/I A
(a) 48.4 km/h [E 78.18 N]
(b) 48.4 km/h [E 11.98 N]
(c) 49.7 km/h [E 80.38 N]
(d) 49.7 km/h [E 9.78 N]
8. The block in Figure 2 remains motionless against
the wall because of an applied force and the force of
static friction between the block and the wall. The
coefficient of static friction is mS. Which equation
correctly describes the magnitude of the frictional
force between the wall and the block? (2.1) K/U A
m
Fa
Figure 2
>
(a) 0 F S 0
>
(b) 0 F S 0
>
(c) 0 F S 0
>
(d) 0 F S 0
>
5 1 0 mg 0 cos u 2 mS
>
5 1 0 F a 0 sin u 2 mg2 mS
>
5 1 0 F a 0 cos u 2 mg2 mS
>
5 1 0 F a 0 cos u 2 mS
NEL
4/26/12 9:55 AM
9. A car and driver with a combined mass of 1.5 3 103 kg
experience a forward force of 7.67 3 103 N and forces
of friction and drag of 7.7 3 102 N. What is the
acceleration of the car and driver? (2.2) K/U T/I A
(a) 4.1 m/s2
(b) 4.6 m/s2
(c) 5.1 m/s2
(d) 5.6 m/s2
10. An object is pushed horizontally at a constant
velocity. What is true about the forces acting on
the object? (2.2) K/U T/I
(a) The force or forces acting forward are greater
than the force or forces acting backward.
(b) The sum of all forces is directed forward.
(c) The forces acting on the object can be said to
be “unbalanced.”
(d) The sum of all forces is zero.
11. A winch pulls a mass of 1.75 3 103 kg up a 248 slope.
Friction is negligible. What is the tension in the
winch cable? (2.3) K/U T/I A
(a) 7.0 3 103 N
(b) 9.0 3 103 N
(c) 1.6 3 104 N
(d) 1.7 3 104 N
12. A force of 1.0 3 103 N moves a heavy box up
a ramp with a 218 incline. The weight of the box is
1.69 3 103 N, and it moves up the ramp at a constant
speed. What is the coefficient of kinetic friction
between the box and the ramp? (2.4) K/U T/I A
(a) 0.02
(b) 0.25
(c) 0.48
(d) 0.71
13. An object is pulled across a rough horizontal surface
with an applied force of 300 N [408 below the
horizontal]. The applied force is slowly rotated up
toward the horizontal, decreasing the 408 angle.
What will happen to the force of friction acting
on the object and the acceleration? (2.4) K/U T/I
(a) Both increase.
(b) Both decrease.
(c) Friction decreases and acceleration increases.
(d) Friction increases and acceleration decreases.
14. For a frame of reference to be inertial, it must
(a) undergo positive acceleration
(b) undergo negative acceleration
(c) change direction without changing speed
(d) move in one direction with constant speed
(3.1) K/U
NEL
8160_CH03_p135-157.indd 149
15. An object moving in a circular path with radius
0.25 m experiences a centripetal acceleration of
2.5 m/s2. What is the frequency? (3.2) K/U T/I A
(a) 0.016 Hz
(b) 0.13 Hz
(c) 0.25 Hz
(d) 0.50 Hz
16. You are spinning two identical balls attached to
strings in uniform circular motion. Ball 2 has a string
that is twice as long as the string with ball 1, and the
rotational speed of ball 2 is three times the rotational
speed of ball 1. What is the ratio of the centripetal
force of ball 2 to that of ball 1? (3.3) K/U
3
(a)
4
3
(b)
2
9
(c)
4
9
(d)
2
Indicate whether each statement is true or false. If you think
the statement is false, rewrite it to make it true.
17. A straight line on a position–time graph indicates
that the acceleration is zero. (1.1) K/U
18. The variables in the kinematics equation
>
> >
1 >
>
>
Dd 5 viDt 1 a 1Dt2 2 are Dd , vi , and a . (1.2) K/U
2
19. The magnitude of the average velocity is always
greater than or equal to the average speed in two
dimensions. (1.4) K/U
20. The time of flight for a projectile fired horizontally from
a given height equals the time it takes for the same
projectile to fall vertically from the same height. (1.5) K/U
21. An FBD shows only the forces acting on an object or
a group of objects. (2.1) K/U
22. According to Newton’s third law, the action force
occurs first, causing an equal and opposite reaction
force. (2.2) K/U
23. For any two materials, the coefficient of static friction
is greater than or equal to the coefficient of kinetic
friction. (2.4) K/U
24. For the apparent weight of a passenger in an elevator
to equal zero, the elevator must accelerate upward at
9.8 m/s2. (3.1) K/U
25. The tension acting on a horizontal string swinging
a ball around in a horizontal circle on a frictionless
>
v2
surface is F T 5 m [toward the centre of the circle].
r
(3.2, 3.3) K/U
26. In a centrifuge, the walls of the test tubes provide the
centripetal force. (3.4) K/U
Unit 1 Self-Quiz 149
4/26/12 9:55 AM