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Name:
PHYS 161 Fall 2024 EXAM I
I pledge on my honor that I have not received or given any unauthorized
assistance on any part of this examination in its whole duration.
Signature _______________________________
- After the exam starts, please do not talk or look around. Try to avoid
situations which may be conjured as attempts to engage in dishonest
activities during exams. Academic integrity is taken seriously by the
University.
- Please print and sign your name to the Honor Pledge above. Do not turn
this page until you are instructed to start.
- When the proctor tells you to begin, print your full name at the top of every
page. This is essential since this exam booklet will be separated for
grading.
- You may have one sheet of paper for equations and a calculator. Please
switch off your cell phone and place all materials directly underneath
your seat, not on the floor or in the seats next to you.
- Do your work for each problem on the page for that problem. You might
find it convenient to do your scratch work on the back of the page before
starting to write out your answer or to continue your answer on the back.
If part of your answer is on the back, be sure to check the box on the bottom
of the page so the grader knows to look for it!
- No points are given if only an answer is given, unless explicitly requested.
Show your work.
- If you run out of time on a problem, indicate the strategy you would have
taken to approach the problem, you may get partial credits for it.
_____________________________________________________________
2 If you need more space, continue on the back and check here.
1. ( 40 points) An object moves along a
straight-line path. The graph to the right
shows the object’s position as a function of
time.
At what point (or points) do the following
conditions apply? If you think that no
points are correct, put an N for that answer.
A. The displacement is zero
B. The velocity is zero
C. The acceleration is zero
D. The speed is increasing
E. The speed is decreasing
F. The acceleration is positive
G. The object is moving to the right
H. The object is moving to the left
F
B
,
D
B
,
P
,
E
,
f C D A A C A ,
t
F
4 If you need more space, continue on the back and check here.
3. ( 10 points) An archer is
training for an Olympic com-
petition. The target is located
40 m to the East of the
archer. The target is 2m tall;
the center of the target is at
the same height as the re-
lease point of the arrows. An
arrow is launched with an
angle 𝜃𝜃 = 30
∘
with respect
to the horizon, and with a speed of 20 m/s.
A. Will the arrow hit the target? If not, where will it hit the ground? ( 5 pts)
B. Which initial speed does the arrow need to have to hit the center of the target?
Which is the minimal initial speed that the arrow needs to hit the target? ( 5 pts)
4m
Xo
z
0
Vox =
1
M/
S
A
)
"
.. .
""
×=
で
Vx
=
.
3
m/s
Voy
=
10
Yo
=
×= 17.
,
0
Y
=
m
a
=
=
01m/S
2
X
=
S
.
X
=
10 f +
i- 9
.
81
2
(
. 81
)
Nos
it
dresnt
hit
Ftnoteematasm
I
=
. 04
B)
×
0
=
0
5
=
40
m
Y
0
= 1
y
=
1
Vox
=
VoCOS
(
Vo
=?
d
=
-9.81m/s
>
Voy
=
Vosin
=
Vox
t
0
=
Vo
.
品
s
30
)
i
9 .
81
) (
℃
s 30
P
Y
ー
VoCos (
30 )
0 =
2
t
⽴
(
9
. 81 )
46
.
2
=
1046 U
·
misJ
004
=
√ .
2
=
227
5 If you need more space, continue on the back and check here.
4. (15 points) At its Ames Research Center, NASA uses
its large “20 G” centrifuge to test the effects of very
large accelerations (“hypergravity”) on test pilots and
astronauts. In this device, an arm 8. 84 m long rotates
about one end in a horizontal plane, and the astronaut
is strapped in at the other end. Suppose that she is
aligned along the centrifuge’s arm with her head at the
outermost end. The maximum sustained acceleration to
which humans are subjected to in this device is typi-
cally 12. 5 𝑔𝑔 (where 𝑔𝑔 represents the acceleration due to gravity on Earth as 𝑔𝑔 =
- 80 m/s
2
A. How fast must the astronaut’s head be moving to experience this maximum ac-
celeration? (5 pts)
B. What is the difference between the acceleration of her head and her feet if the as-
tronaut is 2. 00 m tall? (5 pts)
C. How fast in rpm (rev/min) is the arm turning to produce the maximum sustained
acceleration? (5 pts)
A)
12 .
5
·
9
.
01
=
v
=
1084
29ms)
B
)
ac
=
崎
=ω㎡ω==
3
。
③
723
( 8
= に
3
(
72
)
”
.
84
=
9
V
=- Wr
anta
=
1
misa
_
) ω=
5
.
x ^
w
^
”
!
毆
