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Unformatted text preview: PHYS 121 {SPHJ NAME [print clearly}:
EHM 3 50 pts maximum Discussion Section {required}: You can bring a 3x5 inch index card. Dnly nonprogrammable and nongraphing calculator is allowed. Write iegibiy and present your solutions in an orgonizeci and coherent form. Use pencil.
ir'ou must show all worlc not just the answers. A correct answer alone will receive zero point. '11. An EDrg rubber ball is thrown horizontally with a speed of 5D mfs toward a wall. it is initiallyr
traveling to the left. It rebounds with no loss of speed. The collision force is shown in the top graph
below. Assume to the right as the positive direction. F
a} What is the value of the maximum force Fmax? (3‘ pts} F x
J??? 14; :«H‘M/S max
D':'_éﬂ?_/§ U I
£0 10 m3 fess; I ?”Pf 7f}
w J  ﬁreﬂy/amarr’ipoyN’fﬁ}“Lei/3W?" b} Draw a velocityversus~time graph for the collision on egg/7,5
the given set of axes. Make your graph align verticallyr b
with the force graph, and provide an appropriate J W
numerical scale on the vertical axis. [2 pts] ll] {rims o} Is the collision elastic or inelastic? Why? [1 pt} 11“}; {$th [12%an , 77:5, 236’?" Howls “M M Arts 47/ sffa’é x, ﬁles
ﬂu [9551f W/  If? 3* C12. A elsrvr hall of mass M traveling in the horizontal direction strikes a block of mass 3M that’s
suspended from a light vertical string of length L as shown. Thev stick together and rise until the string
makes an angle of EU“ with the vertical. {Forfoii credit your soiution must include a description ofvour pion forsoiving the probiemfromfundomentoi equations, and an answer to the question posed in the problem. I a} Determine the initial velocityr of the ball, in
terms of anvr or all of the following: M, L,
fundamental mathematical and phvsical
constants. [12 pts} Age #9 aim/wig? 3% Met a;
mWE WW“ M'fw b} What percentage of kinetic energv is lost during collision? [2 ptsi “iii wwwzwugeewg: m 4%
E ii" Warm kmﬁciﬁitﬁ/‘iﬂf :3’4ﬁiizf5ff3 3/41];  l 1g; I. a»
News? = $le ”:"§=%:% ML W
alxj Page 2 of4 {13. The spring In the ﬁgure has a spring constant of 1200 Him. It is compressed at} cm, then launches a
I12 kg block. The horizontal surface is frictionless, but the 4G“ slope Is not frictionless. The block's
coefﬁcient of kinetic friction on the slope is {1.15. What is the total distance will the block travel up the
slope before reversing direction? Solve this problem use work and energvinstead of kinematics. {Forfuii f!
credit your solution must include proper diagrams, description of your plan for serving the problem from I'll
fundamental equations, proper units, and an answer to the question posed in the problem.) [1d ptsl Miriam 7% M53?!) W/
rufﬂe WW2 5W. kf+l§f fﬂfraﬁéw/ aﬂrsﬁﬁmg 7&wa
.. 1 f
r? atmrwwiwmiér =afafﬁ’k/ﬁ) +5 4/” saw/redraw“ “I“ la a
/ 565% .rjjarsmlfd vr/dpy Minis}! 1:: ,§ 4555)} :4:ka
r“ WW 1’ (Mr) (a 5)} .1 5‘4
: tﬁxﬁﬂmﬁﬁrsi’ﬁ’suﬁareﬂé Arrff C14. While the block is moylng up the slope, as in the preyious question a} Draw a freebody diagram showing all the forces acting on the block {1 pt] b} Next to your free—body diagram, make a table showing the sign (1,  or [I] of:
i} the work done by each force in your diagram {1 pt]
ii} the net work whetll pt}
iii} the block‘s change in kinetic energy ME [1 pt} {15. Balls A and B are thrown at a wall ' I same 1irelocity. Ball A bounces and Ball B sticks. Which hall
exerts a larger impulse on the wall? @all B or the same for both? [2 pts} [1.6. Two ice skaters, Brian and Ashley, push off from each other. Brian weighs more than Ashley. a] Which s _ t r if either, has the greater magnitude of momentum after the pushoff? Brian, Ashley or
is it e same rboth? {2 pts} of FL} I l}!P 5
h] Which skater, i either, has the greater speed after the pushwoff? Bria w; or the same for both?
{2 tits} (1?. It feels better to catch a baseball while wearing a padded gloye than to catch it bare handed. Why? iii! MW WW? p. W/J/m 645M clef WW/ Mf/MW $45 {*5/95 Mi
9% #8 whys? Pi wWﬂ ffsnfuécj j/W/ a, Mgzé/fésg 35W
143 armshm 153M . is? mémsﬂ {Xe WW firm/cs, Aw/Zéeé ...
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 Fall '07
 Angerson
 Physics

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