University Physics, 13e (Young/Freedman)
Chapter 3 Motion in Two or Three Dimensions
3.1 Conceptual Questions
1) Shown below are the velocity and acceleration vectors for a person in several different
types of motion. In which case is the person slowing down and turning to his right?
A)
B)
C)
D)
E)
Answer: B
Var: 1
2) While an object is in projectile motion (with upward being positive) with no air
resistance A) the horizontal component of its velocity remains constant and the horizontal
component of its acceleration is equal to -g.
B) the horizontal component of its velocity remains constant and the vertical component of its
acceleration is equal to -g.
C) the horizontal component of its velocity remains constant and the vertical component of its
acceleration is equal to zero.
D) the vertical component of both its velocity and its acceleration remain constant.
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, E) the vertical component of its velocity remains constant and the vertical component of its
acceleration is equal to -g.
Answer: B
Var: 1
3) For general projectile motion, when the projectile is at the highest point of its trajectory A)
its acceleration is zero.
B) its velocity is perpendicular to the acceleration.
C) its velocity and acceleration are both zero.
D) the horizontal component of its velocity is zero.
E) the horizontal and vertical components of its velocity are zero.
Answer: B
Var: 1
4) Alice and Tom dive from an overhang into the lake below. Tom simply drops straight down
from the edge, but Alice takes a running start and jumps with an initial horizontal velocity of 25
m/s. Neither person experiences any significant air resistance. Just as they reach the lake below
A) the speed of Alice is larger than that of Tom.
B) the splashdown speed of Alice is larger than that of Tom.
C) they will both have the same speed.
D) the speed of Tom will always be 9.8 m/s larger than that of Alice.
E) the speed of Alice will always be 25 m/s larger than that of Tom.
Answer: A
Var: 1
5) Alice and Tom dive from an overhang into the lake below. Tom simply drops straight down
from the edge, but Alice takes a running start and jumps with an initial horizontal velocity of 25
m/s. Neither person experiences any significant air resistance. Compare the time it takes each of
them to reach the lake below.
A) Alice reaches the surface of the lake first.
B) Tom reaches the surface of the lake first.
C) Alice and Tom will reach the surface of the lake at the same time.
Answer: C
Var: 1
6) Jan and Len throw identical rocks off a tall building at the same time. The ground near the
building is flat. Jan throws her rock straight downward. Len throws his rock downward and
outward such that the angle between the initial velocity of the rock and the horizon is 30°. Len
throws the rock with a speed twice that of Jan's rock. If air resistance is negligible, which rock
hits the ground first?
A) They hit at the same time.
B) Jan's rock hits first.
C) Len's rock hits first.
D) It is impossible to know from the information given.
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Chapter 3 Motion in Two or Three Dimensions
3.1 Conceptual Questions
1) Shown below are the velocity and acceleration vectors for a person in several different
types of motion. In which case is the person slowing down and turning to his right?
A)
B)
C)
D)
E)
Answer: B
Var: 1
2) While an object is in projectile motion (with upward being positive) with no air
resistance A) the horizontal component of its velocity remains constant and the horizontal
component of its acceleration is equal to -g.
B) the horizontal component of its velocity remains constant and the vertical component of its
acceleration is equal to -g.
C) the horizontal component of its velocity remains constant and the vertical component of its
acceleration is equal to zero.
D) the vertical component of both its velocity and its acceleration remain constant.
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, E) the vertical component of its velocity remains constant and the vertical component of its
acceleration is equal to -g.
Answer: B
Var: 1
3) For general projectile motion, when the projectile is at the highest point of its trajectory A)
its acceleration is zero.
B) its velocity is perpendicular to the acceleration.
C) its velocity and acceleration are both zero.
D) the horizontal component of its velocity is zero.
E) the horizontal and vertical components of its velocity are zero.
Answer: B
Var: 1
4) Alice and Tom dive from an overhang into the lake below. Tom simply drops straight down
from the edge, but Alice takes a running start and jumps with an initial horizontal velocity of 25
m/s. Neither person experiences any significant air resistance. Just as they reach the lake below
A) the speed of Alice is larger than that of Tom.
B) the splashdown speed of Alice is larger than that of Tom.
C) they will both have the same speed.
D) the speed of Tom will always be 9.8 m/s larger than that of Alice.
E) the speed of Alice will always be 25 m/s larger than that of Tom.
Answer: A
Var: 1
5) Alice and Tom dive from an overhang into the lake below. Tom simply drops straight down
from the edge, but Alice takes a running start and jumps with an initial horizontal velocity of 25
m/s. Neither person experiences any significant air resistance. Compare the time it takes each of
them to reach the lake below.
A) Alice reaches the surface of the lake first.
B) Tom reaches the surface of the lake first.
C) Alice and Tom will reach the surface of the lake at the same time.
Answer: C
Var: 1
6) Jan and Len throw identical rocks off a tall building at the same time. The ground near the
building is flat. Jan throws her rock straight downward. Len throws his rock downward and
outward such that the angle between the initial velocity of the rock and the horizon is 30°. Len
throws the rock with a speed twice that of Jan's rock. If air resistance is negligible, which rock
hits the ground first?
A) They hit at the same time.
B) Jan's rock hits first.
C) Len's rock hits first.
D) It is impossible to know from the information given.
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