Physics 011
Chapter 3: Kinematics in Two Dimensions; Vectors
Practice Questions
PQ#3

If you drive west at 20 km/h for one hour, then drive east
at 15 km/h for one hour, your net displacement will be 


5
km east. 


35
km west. 


35
km east. 


5
km west. 




A 200lb force is pulling on an object, as shown. The sign
of the x and y components of the force are 


x
(positive), y (positive). 


x
(positive), y (negative). 


x
(negative), y (positive). 


x
(negative), y (negative). 




Three boys each pull with a 20N force on the same object.
The resultant force will be 


zero. 


20
N to the left. 


20
N up. 


20
N down. 




Consider a plane flying with groundspeed Vg and airspeed
Va in a wind with speed V. Which of the following relationships is true? 


Vg
will always equal Va + V 


Vg
can be greater than Va + V 


Vg
can be less than Va  V 


Vg
can have any value between Va + V and Va  V 




Two vectors, R and S, are known: If vector S is subtracted from vector R, the vector T = R
 S is 
















Two vectors, R and S, are known: If vector R is subtracted from vector S, the vector T = S
 R is 
















Two vectors, R and S, are known: If vector S is added to the vector R, then the vector T =
R + S is 
















If the acceleration vector of a body is perpendicular to
the velocity vector, which of the following must be true? 


The
speed is changing. 


The
direction is changing. 


Both
the speed and the direction are changing. 


The
direction is not changing. 




A vector of magnitude 10 has an angle with the positive
xaxis (East) of 120 degrees. What are its components? 


5
and 8.7 


5
and 8.7 


5
and 8.7 


5
and 8.7 




A vector of magnitude 10 has an angle with the positive
xaxis (East) of 60 degrees. What are its components? 


5
and 8.7 


5
and 8.7 


5
and 8.7 


5
and 8.7 




A vector has components x=6 m and y=8 m. What is its
magnitude and direction? 


10
m and 30 degrees 


14
m and 37 degrees 


10
m and 53 degrees 


14
m and 53 degrees 




A vector has components x= 2 m and y=2 m. What is its
direction (angle with respect to East)? 


45
degrees 


135
degrees 


225
degrees 


45
degrees 




Three vectors have components (x,y):A=(2,3),B=(4,7)
and C=(6,3). What is the magnitude of the resultant vector (D=A+B+C)? 


7 


17.7 


15 


7 




Three vectors have components (x,y):A=(2,3),B=(4,7)
and C=(6,3). What is the magnitude of the resultant vector (D=ABC)? 


13.6 


15 


52 


7 




Suppose that several projectiles are fired on level
ground. Which one will be in the air longest? 


The
one with the farthest range, R. 


The
one with the highest maximum elevation, h. 


The
one with the greatest initial velocity. 




Which of the following does not affect the range of a
projectile? 


v_{o}
Initial Speed 


theta_{o}
Launch Angle 


y_{o}
Initial Height 


x_{o}
Initial Horizontal Position 




Which of the following must be zero for a projectile to
achieve its maximum range? 


v_{xf} 


v_{yf} 


x_{f} 


y_{f} 




Which of the following must be zero for a projectile to be
at its maximum height? 


v_{xf} 


v_{yf} 


y_{f} 


x_{f} 




You hit a handball too hard and it lands, moving
horizontally, on top of a roof. If its original velocity was v_{o} at
an angle q above the horizontal, then the velocity it lands on the roof with
is 


zero 


v_{o}
sin q 


v_{o}
cos q 


2v_{o} 




You throw
a pebble upward as shown, with a velocity v_{o} at an angle theta,
from a roof (at point J) h ft above the ground. If the pebble rises upward to
h ft above the roof (to point K), then falls to the ground below (to point
L), its speed when it hits the ground is 


v_{o}. 


between
v_{o} and 2v_{o}. 


2v_{o}. 


greater
than 2v_{o}. 




Taking "up" as positive at the highest point,
the acceleration of a projectile is 


9.8
m/s^2 


0
m/s^2 


+9.8
m/s^2 




If the sum of two vectors equals zero, the magnitude of
their difference is 


equal
to the magnitude of either one. 


equal
to twice the magnitude of either one. 


less
than twice the magnitude of either one. 




A sailboat travelling with a speed of 4 knots heads
directly up river against a 3 knot current. Its speed over ground is 


1
knot. 


7
knots. 


3
knots. 


5
knots. 




A sailboat travelling with a speed of 4 knots heads
directly down river with a 3 knot current. Its speed over ground is 


1
knot. 


3
knots. 


5
knots. 


7
knots. 




A sailboat travelling with a speed of 4 knots heads
directly across a river which has a 3 knot current. Its speed over ground is 


1
knot. 


3
knots. 


5
knots. 


7
knots. 