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Unformatted text preview: MC
15/ Fall 2003 Last Name
Physics 175
Exam #1 First Name ID # Points for each question are indicated in parentheses. Show your work for solutions to questions that
require calculations. Explain from where you start to solve the problem and show your math ﬂowing
from it for full credit. Surround your result in a box and don ’t forget to include the units for your result.
If you need more space to ﬁnish a question, write BPP (Back of the Previous Page) at the end of the
space provided and then complete your work on the back of the previous page. For multiple choice
questions, circle the letter which you believe to be correct (or best). In all problems, take the
gravitational acceleration g = 10 m/sz. 1. (3 points) A juggler throws two balls to the same height so that one is at the halfway point going up
when the other is at the halfway point coming down. At that point:
a) Their velocities and accelerations are equal.
b) Their velocities are equal but their accelerations are equal and opposite.
@ Their accelerations are equal but their velocities are equal and opposite.
(1) Their velocities and accelerations are both equal and opposite.
e) Their velocities are equal to their accelerations. 2. (3 points) A large beach ball is dropped from the ceiling of a school gymnasium to the ﬂoor about 10
meters below. Which of the following graphs would best represent its velocity as a function of time? '5" V V V V
0L [IQ 0Q 11K [IE
I] 1 I] t [I l I] 1 l] t
[31 [Cl [3] [E] 3. (3 points) A truck driver travels threefourths the distance of his run at one velocity (V) and then
completes his run at one half his original velocity (1/2v). What was the trucker’s average speed for the
trip? , .
a) 0.85V 0.80v 0) 0.75v (1) 0.70v e)0.65v 4. (3 points) A child tosses a ball directly upward. Its total time in the air is T. Its maximum height is H.
__.W_hat is its height after it has been in the air a time T/4? Neglect air resistance. A.f(1/4) H B. (1/3) H C. (1/2) H D. (2/3) H @(3/4) H 5. (3 points) The accompanying ﬁgure is a graph of an '
object’s position as a function of time. Which lettered
segment corresponds to a time when the object has a
negative acceleration?
a) A
“b) B
G) c
d) D
e) E 6. (15 points) You are standing on the edge of a cliff of height H. You throw a ball at an angle 9 = 30°
above the horizontal with an initial speed of v0 = 54 m/s. Using a stop watch, you determine that the ball
strikes the ground at the base of the cliff at time t = 7 s aﬁer release. Make a schematic drawing of the
problem indicating on the ﬁgure the physical quantities given in the problem. a) What is the horizontal distance, D, covered by the ball? b) At what time, T, does the ball reach its maximum height? 0) What is the height, H, of the cliff? ~ A J w—V ¢~57
“OVA 7;: YVchSlJEJ’v‘lJC 7. (10 points) The velocity of a particle moving along the x axis is given for t > 0 by vx = (1 8t — 2t3) m/s,
where t is in 8. What is the acceleration of the particle when (aﬁer t = 0) it achieves its maximum
displacement in the positive x direction? sip new W AK M 0%; r k}
NDQLKNW égx thKkCXW \U : O ’ x :9 o titer? =3 @etz\'ZJC=O 371+? 3% ol‘v‘x; +95 :3 a : ii/cawgé
“at lg l 8. (10 points) A 0.20km wide river has a uniform ﬂow speed of 3.0 m/s toWard the east. A boat with a
speed of 5.0 m/s relative to the water leaves the south bank and heads in such a way that it crosses with a constant velocity to a point directly north of its departure point. How long does it take the boat to cross
the river? y plane in a circle centered on the origin. At a certain instant the velocity is 6.0i m/s and the acceleration of the particle is (3 i + 4 j) m/sz. What are the x and y
coordinates of the particle at this moment? A by x=0,y=—9.0m
b x=0,y=+7.2m \ p A ‘&9 mgwa
®x=0,y=+9.0m/¥ \8 Wire “3‘
d) x=0,y=—7.2m
e) x=6.0,y=—9.0m IO. (5 points) A car travels counterclockwise around a ﬂat circle of radius 0.25 km at a constant speed of 20 m/s. When the car is at Skirer 20 m/s
point A as shown in the ﬁgure, what is the car’s acceleration? I I ’ ‘ x
a) 1.6 III/$2, east q A [I X
b) Zero 2 a=0g Kkﬂat=0 I \
a; 12min 2 comm. est, A
@I.6m/sz,west A in (if 2 16) \LL ‘\ / QR 1
GK“ {2 ' V2150 ‘ 52 \\ R=O.25 km I,’
\ I
w ‘ ~   ’
a: QR: H; 9 South 11. (10 points) Vectors A andB are shown. What is the magnitude and direction of a vector C if
C = A — B ? Show the direction of vector C and the angle it makes on a schematic diagram. .» 4 J)
C2 Avg 0 CX‘AX’BX: AICOBQDQ’B A
K 40
60°
50
J “K
C
G >4 Bonus question (5 points 2 Driving down the highway you ﬁnd yourself behind a heavily loaded tomato truck. You follow close
behind the truck, keeping the same speed. Suddenly, a tomato falls from the back of the truck. Will the tomato hit your car or land on the road assuming you continue moving with the same speed and in the
same direction as the truck? Explain. . ...
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 Physics, Acceleration, Velocity, #, $2, 0%

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