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Unformatted text preview: Tl 0M Total grade: PH 1110 Summary Homework 2, C Term 2008 Name Section Number This assignment is worth 2.5% of your ﬁnal grade and is our recommended means for you to assess
your readiness for Exam 2. It is due in conference on Tuesday, January 29 and will be returned to you in conference on Thursday, January 31, the day before Exam 2. Please show your work and report your answers to no more than three signiﬁcant ﬁgures. la. [10 pts] You want to reenact Galileo’s famous experiments with gravity. Instead of tossing masses of
different sizes and weights, you use rotten tomatoes. You ﬁnd a way onto the roof of Olin Hall, above
a section of lawn. You realize that the tomatoes will make more dramatic Splats if you were to throw
them onto the concrete walk a few meters away from the base of the building. For an initial height h =
19.6 In, and a minimum horizontal travel distance ofxmil1 = 5.00 m, what minimum horizontal speed
vxm'“ should you give a tomato for it to land on the concrete? You launch the tomato in the horizontal direction. Please write your answer in the box. 1
,‘ _L 
Vi 1" ‘40 4 Unit 4 Lat—f
l ‘7. czkaowagt Tomato’s
initial position «reﬁt? :5 ﬂights
x = VH1?
5 ' Vexf :Vox (Z)
Xmin Vols I E‘s—0 m/S 1b. [10 pts] Then you realize that you could inspire more awe in passers—by if you were to launch a tomato at an angle 45° above the horizontal. What minimum horizontal speed vxmi“ is necessary now? Please place your answer in the box. 1
2
.1 .62
0 1 h + Voof'ﬁ ' Lj
Vex—t :7 3.00 f—E—i @ ; 5/30) V¢x5Voq7 ,L\_V”f : 1315?
watt A610 ﬁ—ajfl vxminzi 1  ' Points earned on this page: C! Section Numb er Summary Homework 2, continued. Name 2a. [10 pts] A car of mass m traveling at a constant speed v slides on an icy patch of road (no ﬁiction)
where the road curves in a half~circle with a radius r. The road is banked at an unknown angle 6. The
car slides neither up nor down the bank throughout the tum. Draw on the sketch below the vectors
representing the forces acting on the car (represented by the rectangle) and label them. M
NO 9 il ' Side View of car on a banked curve ﬁ’dllr O = Namemj
L? X’Olli’” NSine : MVL/R 2b. [10 pts] Write out Newton’s Second Law for each of the directions indicated by the coordinate
system. 20; [10 pts] Solve for the unknown angle 9, and write your answer in the box below. EVEm O N 3* Ma/csma
m3 87V} 6 i, M V2 ‘
_ Z) . c.3175. A
' ' .1
WW 2 .  Points earned on this page: E ,.—\\ Summary Homework 2, continued. Name Section Number 3a. [10 pts} In Lab 3 you measured how your effective weight changed as you moved your forearms
while you stood on the force plate. Below are rectangles representing your forearms, the entire rest of
your body, and the force plate. Please draw vectors representing the forces acting on them. Assume
that your arms were positioned symmetrically, such that all horizontal forces cancel. In other words,
you need to draw vectors only up or down. Clearly label each force uSi'ng the form F A on B, where “A on B” means Object A acting on Object B. r
'5'“ Fplmile W IMAM) Paws“ m imiﬂ Force plate Foreanns Body 3b. [10 pts] Now please draw sketches of the reaction forces to each force drawn above, also using the
form F A on 3. Alternatively, you are allowed to describe the reaction forces in complete sentences. f. E71 m 147m Me cmfﬂ, w W) b917) 5,141 "his Fe.a,df‘;m M % e/a Wat/Ml Fence a? ﬁe
I W j bani/’1 ) M /‘/Q7£€ '5’“ 7%? Q4421]: W‘W M m M. M ac?!de "
ﬂ/Zaz/fgcnn *6‘1‘ f" . FIE/“Ag 5729,17 {35,067 Inf/427% I
 {aeolrvm flaw" ' F’f’hvr cm / 41%? r‘ 7‘ “Flame W‘ 4/3”“ 3 ' _' Points earned on this page: _ l:' !/'"\ 2;) carat )xﬂlrr Summary Homework 2, continued. Name Section Number 4a. [10 pts] In Lab 4, the masses and hanger are connected to the cart by a string, just as in the picture in
the overview of the lab instructions, or as in the sketch on the left below. PleaSC draw vectors representing the forces acting on of the masses and hanger (mh), as well as the cart on the steeply
_sloped track (Inc), making sure to label the forces clearly. T T N PR“ 'W‘j We? Experimental setup Masses and hanger Cart at rest and in e uilibrium 4b. [10 pts] Then based on these freebody diagrams, write out Newton’s Second Law for equilibrium of the hanger, and equilibrium of the cart along and perpendicular to the track. Indicate the coordinate
systems that you use with clearly labeled vectors near the diagrams above. 0 tor/‘39,] can ozamnj +7
2'1 Ogmcﬁsln}eT‘UD 3) CU” ,clviélr" G : N1 M9 W 4c. [10 pts] Use the above equations to solve for the magnitude of the friction force, eliminating the
variable that represents tension in the string. Place your answer in the box below. m 9H 2) Olmcjslmr) whj ~ 70.
I —? = j(mc5‘iineWlh) \
[é sic/+2.“ :5 :tr ' ow has; Friction magnitude '——“ (ma 8 I‘h Q “My, l
4_ _.  ' Points earned on this page: [:i ...
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 Spring '08
 Keil

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