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**Unformatted text preview: **Physics 111 Exam 1, Spring 2016 [MC Questions: 2 pts each for a total of 28 pts}
{Ihoese the one ietter that best answers the question and write it on the line to the right. 1. A package faiis off a truck that is moving at 30 m/ s. Neglecting air resistance, the horizontal 1. l2
speed of the package just before it hits the ground is
A. zero. B. more than 30 m/ s.
C. less than 38 m/s but more than zero. W
2. If a car increases its velocity fr F“; o 60 m/ s in 18 seconds, its acceleration is 2. l3
A. 60 m/sz. @ c. see misﬁ. 13.3 m/SZ. we “-9 ‘22
3. if the JC-"COIY’FPOHEENZ of vector P and the arc-component of vector Q have equai magnitudes but 3.
opposite signs, and both vectors have identical y‘componeots. Which one of the following statements about these two vectors is correct? “1* "'3‘ _ . . . .
AVectors P and Q pomtm opposxte directions. nu}
B. The magnitude of vector P is twice the magnitude of vector Q .
.m; E. Vector P is paraiiei to vector Q . 4. The motions of a car and a truck along a straight road are represented by the velocity-time 4. D
graphs in the figure. The two vehicles are initially alongside each other at timet : 8. At timeT,
What is {me about these two vehicies since time: = 0? Truck Car mun-w..— 0 T A. The car wiii have traveled further than the truck.
3. The car will. be traveiihg Easter than the truck C ﬁmsemmammmee same distance. D. The truck wiii ihave traveled further {Mum
.. WWMM MP” 5. If a stone felts to the bottom of a mineshaft in 6 secondsihenﬁqth: depth of the shaft is about
A, 120 m. @125)
C. 60 m. D. more an 200 m. 6 A hockey puck is set in motion across a frozen pond. if ice friction and air resistance are 6. \ g
neglected the §orce required to keep the puck sliding at constant veiocity' is A. equal to its Weight divided by its mass. 13. e i—touit miss its weight
C. equal to its weight. t). none of exit?) 7. The equiiibrium rote, ELF = O, appiies to
A. obiects or systems at rest.
9%bgltsoc. stems in uniform motion in a straight iine. (Loth of these”;
D. neither of these 8. When can we be certain that the average velocity of an object is always equal to its
instantaneous velocity?
A. oniy when the acceieration is constant
B. oniy when the acceieration is changing at a constant rate
C. always
D. never K“ . only when the velocity is constant\\) 9. The force exerted on the tires of a car that directly accelerate it aiong a road is exerted "by the A. tires.
8. air. Ci eases-
d/if weight) E. none of the above 10. l Teiiie pulls with a force of 50 N on a horizontal rope tied to a tree at rest. The net force on the rope is
A. 58 N and rope tension. is 0 N. B. 50 N and rope tension is also 50 N.
C. zero and rope tension is aiso zero. C lgjemandW; 1 i. Whatmust be true in order for two non—zero vectors to have a dot product and a cross product
with the same magnitudes?
A. The two vectors are eﬂiﬂﬂﬂlﬂﬂ_
anfﬁéW»
C. The two vectors are anti«parallet.
D. Two non-zero vectors can never have a dot product with the same magnitude as their
cross product.
E. The two vectors are perpendicular. 12. Whiie a car travels around a circular track at a constant speed, its A. acceieration is zero. 3. VW_
@f the ab «e C. inertia is zero. 0M 13. Ioshua is attracted toward Earth by a 500~N gravitational force. The Earth is attracted toward new force of . 00 N. B. 250 N. C. 1000 N. D. zero. 14. A heavy block at rest is suspended by a verticai rope. When. the block accelerates upward by the
rcpe, the rope tension
A. equals its weight.
B. is less than its w i ht. @greater than its weighif} WM— 10. 11. 14. '0 4%.. we 2. (24 points) Vectors. Show your work and explain year reasoning.
Consider the vectors A, B, and D as shown. a + is? — e «= '07
V ‘ magnitudes/4:720
A?» Base
3 9:12 ! a. (6 39153) Find the 1"- and yucomponents of vectors .3, B, and 5. Are tweowivswew maria Afaw amtomewwew own 13. (12 pts) Find the magnitude and direction of a vector 5' that would make this statement --9 true: A+B C t D. Express your answer for direction (as degrees from the +x‘-axis toward the +y-axis):
k f: if”; £15 ”mg (K e Ax +3” «a; e imswno s-—'?.“?é
Q a». a? «at? wt}, :2 “Wessex-75
)5) V " = 8123' e *2 IW» ans/Eff = mom/aw M c. [6 pts) The sketch shows the. position of the moon at two times, about seven days apart. “- i 60. $30
The veiocity vector for the 111001: at each of these times is shown. Find the direction of the change
in velocity of the moon over the time interval between t1 and t2. Indicate the direction by
drawing a vector to a similar scale as those shown. If the Change in velocity is zero, state
that expiicitiy. 3. (24 points) Constant acceleration. Show your work and explain your reasoning.
Beginning with the deﬁnition of acceleration, do
an; m dim 4 derive the equations for vm(t) and 59(15) for constant acceleration in the set—direction. In your derivation,
denote the initial position x(t = 0) as 339 and 24(t m 0) as 4103. (Writing down the equatioes from memory
is not adequate fez" csedit on this problem.) a. (8 pts) Derive the equation for 143,05 and identify the constant of integration . (Dc-M ETI‘H‘J‘T WWW. also, A ﬂiyoixff {M gees/ems invewe’rﬁ g ‘
’ ﬂ «(gm b. (8 pts) Derive the equation for $05}, and identify e constant of integration. ”4* 4:42;. 4 4 4.4.4445 Z OEFfMiTFDIKS ._.,.._-. "U;
S‘Wmswg f WTE’GYE A'ﬁ; ; V” e. j\-\};d£ 4.44.444ch 4s CZ? LESBAT
E . 40-,“ $0
5597" New ""0 We: V {Er {11% W )1“ 2 s44
X 14.: - WW" } Y Ye 41ti4wm‘i c. (8 39455) A cart moves on an inclineé, straight track with constant negative acceleration.
At time t m 0, it has positive veiocity at position a: : +2.0 m. Sketch the 3: versus 23, '0 versus t, and (1
versus t graphs for the motion given by this description. . . g' 6- -' i rat" . ‘
Constant nebaove gaggﬁ 14341 a V6 ﬁgmjvﬁgf ”“936
L& W W .5” we; 9:1 Maw W 5:4..an
(st-to“! We ..
semmevxw) 4. (24 points) Projectiles. Show your work. and explain your reasoning. A quarterback throws a pass dewnﬁeld {which we can call the positive x-directien). The intended re~
ceiver doesn’t catch the brill= and it hits the ﬁeld untouched by any player. Assume the football ieaves the
quaxterbeck’s hand at a height of 2.3 meters, with an initial veiocity of 14.0 m/s directed at 20" above the horimataé. Ignore air resistance. a. (10 pts) At what time does the bail reach its maximum height, and what is this maximum height? V “1!“! .9203
“freak : “if g 2i“? gﬂ. 14;? sewage j “7.? ngk 3 V9 4' Wy ﬁred ... 'gffik
g 3.3 + (14-. WMQW) ~ Hammer? -== 3.141“? mm b. (10 pts) How far down. the ﬁeld (in meters} does the bail travel befere hitting the ground?
+94%! West in. am a .3 * “ffgak '4' {mm L? A3 ,E E!" a: Wﬁ‘fﬁc 4- $.91}:
quéméaé eqvat::7i » $9 iﬁrﬁm ‘fmemé': 035 femés a .2 [ii-94 sun 29‘) i_ 33 Sﬁﬁwﬁ§
wiggle! We a vm mm; = (23+. & m 20’)(!.§3) a 1‘7. 5 c (4 pts) Two toy trucks roll 0% the ends of identical tables. The speeds and masses of the WW +015
trucks are given. Wili Truck A be' in the air for a longer, a shorter, or the same time as Truck ‘13 before it reaches the floor? Explain WWW Same 1486”‘é;.i( 1%: -' ml? éqenés M
IE3}?! m5 :9 N ma, [em-tetra (not Mass W Am; if) 5. (24 points) Motion equations for non-constant acceleration. Show your work and explain your reasoning.
A student is told that the motion of an object is described by the following equation: 56(15):”4 m+(9 3:1) :‘(2 552‘) t2 a. (6 pts) What are the equations that describe the obg‘ect’s velocity and acceleration at various
times? £195“ ”a“? ’06) 1 0! 3%? WG{ ?%}%
h‘iti 99"”?5‘ (1(15) 3 W q“ 4:ng {ﬁgﬁﬂfﬁWﬁ} b. (8 19153) Is the initiai acceleration 1n the positivewm oﬁégahgiaa direction? 0. (3 pets) Is the initial velocity in [email protected];a> or negative-w direction? we
age We he m S
d. (3 pie) Is the initial position in the positive—x 01: negeﬁijgt direction from the origin? W L{ m1 M «g 2;"- if? e. (3 p158) xifter 3 seconds, 1s. the acceleration 111 the positive or/Wirection? "rs-WW ......... “WM f. (3 p153) After 3 seconds, is the velocity in the positive [email protected]‘ection? ...

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