Word ```S432 Physics
Vectors 2D practice MC
22 pages
Choose the best answer to each question and write the appropriate letter in the space provided.
1) A vector is a quantity that has __________.
A) time and direction.
B) magnitude and time.
C) magnitude and direction.
________
2) A scalar is a quantity that has __________.
A) color. B) direction.
C) time. D) magnitude.
________
3) When representing velocity as a vector __________.
A) the direction of the arrow shows the direction of motion.
B) the length of the arrow is drawn to a suitable scale.
C) the length of the arrow represents the speed.
D) all of the above
E) none of the above
________
4) Which of the following would NOT be considered a projectile?
A) A cannonball rolling down a slope
B) A cannonball thrown through the air
C) A cannonball thrown straight up
D) A cannonball rolling off the edge of a table
E) All of the above are projectiles.
________
5) The horizontal component of a projectile's velocity is independent of __________.
A) the range of the projectile.
B) the vertical component of its velocity.
C) time.
________
6) In the absence of air friction, the vertical component of a projectile's velocity doesn't change
as the projectile moves.
A) Always false
B) Sometimes true
C) Always true
________
7) In the absence of air friction, the horizontal component of a projectile's velocity doesn't
change as the projectile moves.
A) Sometimes true
B) Always false
C) Always true
________
8) At the instant a ball is thrown horizontally with a large force, an identical ball is dropped
from the same height Which ball hits the ground first?
A) Neither -- they both hit the ground at the same time.
B) The dropped ball
C) The horizontally thrown ball
________
9) A ball is thrown into the air at some angle. At the very top of the ball's path, its velocity is
__________.
A) entirely vertical.
B) entirely horizontal.
C) There's not enough information given to determine.
D) both vertical and horizontal.
________
10) In the absence of air resistance, the angle at which a thrown ball will go the farthest is
__________.
A) 75 degrees.
B) 15 degrees.
C) 60 degrees.
D) 30 degrees.
E) 45 degrees.
_______
11) A ball thrown in the air will never go as far as physics ideally would predict because
__________.
A) air friction slows the ball.
B) gravity is acting.
C) one can never throw the ball fast enough.
D) ideally the ball would never land.
E) all of the above
_______
12) At what part of a path does a projectile have minimum speed?
A) When it is thrown
B) There's not enough information to say.
C) When it returns to the ground
D) Halfway to the top
E) At the top of its path
_______
13) A cannonball is launched from the ground at an angle of 30 degrees above the horizontal
and a speed of 20 m/s. Ideally (no air resistance) the ball will land on the ground with a speed of
__________.
A) 20 m/s.
B) There is not enough information to say.
C) 0 m/s.
D) 10 m/s.
E) 40 m/s.
_______
14) A projectile launched horizontally hits the ground in 0.5 seconds. If it had been launched
with a much higher speed in the same direction, it would have hit the ground (neglecting the
earth's curvature and air resistance) in __________.
A) 0.5 s.
B) less than 0.5 s.
C) more than 0.5 s.
_______
15) An airplane flying into a head wind loses ground speed, and an airplane flying with the wind
gains ground speed. If an airplane flies at right angles to the wind, then ground speed is
__________.
A) less. B) more. C) unchanged.
_______
16) Jose can jump vertically 1 meter from his skateboard when it is at rest. When the skateboard
is moving horizontally, Jose can jump __________.
A) no higher. B) higher.
_______
17) Which best approximates the resultant of a pair of 10-unit vectors at right angles to each
other?
A) 20 N. B) 10 N. C) 14 N. D) 0 N.
_______
18) What is the resultant of a 4-unit vector and 3-unit vector at right angles to each other?
A) 5 units. B) 7 units.
C) 1 unit. D) none of the above
_______
19) When in orbit, a satellite like the space shuttle is __________.
A) free from earth's gravity.
B) in non-accelerated motion.
C) simply a projectile.
_______
20) "Hang time," is the time a jumper's feet are off the ground in a vertical jump. If the jumper
runs horizontally and has the same vertical component of takeoff velocity, hang time will be
__________.
A) decreased. B) increased. C) no different.
_______
21) If you could throw a baseball horizontally at a speed of 8 km/s and if there were no air drag
and nothing to stop it, __________.
A) it would escape Earth.
B) it would orbit Earth.
_______
22) Suppose a small plane can fly at 200 km/h relative to the surrounding air. Suppose also that
there is a 40-km/h tailwind. How fast does the plane's shadow move across the ground?
A) 200 km/h
B) 160 km/h
C) 240 km/h
D) 5 km/h
E) 40 km/h
_______
23) At the instant a ball is thrown horizontally with a large force, an identical ball is dropped
from the same height. Which ball hits the ground first?
A) The dropped ball
B) Neitherminusthey both hit the ground at the same time.
C) The horizontally thrown ball
_______
24) A cannonball is fired at some angle into the air. In the first second it moves 10 meters
horizontally. Assuming it doesn't hit the ground and air resistance is small, how far does it move
horizontally in the next second?
A) Less than 10 m
B) There's not enough information to say.
C) More than 10 m
D) 10 m
_______
25) In the absence of air resistance, the angle at which a thrown ball will go the farthest is
__________.
A) 45 degrees.
B) 60 degrees.
C) 30 degrees.
D) 15 degrees.
E) 75 degrees.
_______
26) A ball is thrown straight upward at 20 m/s. Ideally (no air resistance), the ball will return to
the thrower's hand with a speed of __________.
A) 40 m/s.
B) There is not enough information to say.
C) 0 m/s.
D) 20 m/s.
E) 10 m/s.
_______
27) A cannon with a barrel velocity of 100 m/s launches a cannonball horizontally from a tower.
Neglecting air resistance, where will the cannonball be 1 second later?
A) 50 m downrange
B) 98 m downrange
C) 490 m downrange
D) 100 m downrange
E) none of the above
_______
On a separate sheet of paper, answer the following questions.
28) A plane flies north at 200 km/h. At the same time, there is wind of 50 km/h from the west.
Use both the graphical method and the Pythagorean Theorem to find the resultant velocity of the
Answer the following questions in the space provided. Show all work.
29) A boat is rowed at 4.0 km/h directly across a river in water that is flowing at right angles at
8.0 km/h. What is the resulting speed of the boat?
_____________
30) Harry accidentally falls out of a helicopter that is traveling horizontally at 60 m/s. He
plunges into the water below 3.00 seconds later. Assuming no air resistance, what is the
horizontal distance he travels while falling?
_____________
31) Harry jumps horizontally from the top of a building that is 20.0 m high. He hopes to reach a
swimming pool that is at the bottom of the building, 14 m horizontally from the edge the
building. If he is to reach the pool, what must his jumping speed be?
_____________
32) An airplane whose airspeed is 200 km/h flies parallel to the direction of a wind with a speed
of 90.0 km/h. What are the two possible speeds of the plane relative to the ground?
_____________
33) Consider an escalator at an angle of 45degree above the horizontal that moves with a
velocity of 3.0 m/s. What is the vertical component of the escalator's velocity?
_____________
34) A ball is thrown horizontally from the top of a tall cliff. Neglecting air drag, what vertical
distance has the ball fallen 3.0 seconds later?
_____________
35) A ball rolls off the edge of a horizontal roof at a velocity of 10 m/s. What is the speed of the
ball one second later?
_____________
36) A projectile shot with an initial velocity of 101 m/s at an angle of 45degree follows a
parabolic path and hits a stationary balloon at the top of its trajectory. With what speed does the
projectile hit the balloon?
_____________
37) A ball is thrown upward. Its initial vertical component of velocity is 41 m/s, and its initial
horizontal component of velocity is 10 m/s. What is the ball's speed one second later?
_____________
38) A ball is thrown upward. Its initial vertical component of velocity is 61 m/s, and its initial
horizontal component of velocity is 10 m/s. What is the ball's speed two seconds later?
_____________
39) A ball is thrown upward. Its initial vertical component of velocity is 73 m/s, and its initial
horizontal component of velocity is 10 m/s. What is the ball's speed three seconds later?
_____________
40) In a standing jump, the hang time of a certain athlete is 0.6 second. What is her hang time
when she jumps the same height while moving horizontally?
_____________
28) Answer: Resultant velocity of the plane = sqrt(200 to power of (2)plus50 to power of (2))
km/h = 206 km/h. In general, the graphical method will not be as precise as the analytical
method. However, the answers should be within a few percent of each other.