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Unformatted text preview: Part C — Extended Problems — 88 Points Total Cl ([6 points) “a A toy gun ﬁres a plastic pellet with a m'ass 01°05 g. The pellet is propelled by a spring with a spring
constant of 1,25 N/cm which is compressed 2.,0 cm before ﬁring. The plastic pellet travels horizontally
[0 em down the barrel (from its compressed position) with a constant friction force of 0.0475 N o osin the motion of the elletr
pp g p WUODCJS K3 k = 1.25 N/cm d : 10 cm travel {—————_~——) “in: x : 2 cm compression The toy gun is held [.0 m above the ﬂoor. How far does the pellet go horizontally from the point it
leaves the barrel until it hits the ﬂoor? Use g = 9.8 mils2 and neglect air resistance. I Wt“ E{\“?‘,_!_\3\_]L pbb' 6‘13..le {Ageing
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5‘. Problem C (32 Points) — Target Practice A cannon with a ﬁxed launch angle of 18.4350 above horizontal must hit a target that is dropped from
rest by helicopter, The target’s initial position is a horizontal distance (X) of 1500.0 m and a vertical The initial speed of the cannon ball as it leaves the cannon is 158 distance PI) of l 1 12.5 m from the initial position of the cannon ball. (See the ﬁgure.)
.11 m/s. Use g = 9.8000 m/s and neglect air resistance. In order to hit the target, the cannon ball must be within 0.1 m of it. Show that the cannon ball will hit the target if the cannon is ﬁred the time (measured starting from the target drop) of the collision. 0+ MM 0531' cannon ﬁred at x
t: 5.000 sec,” 0= 18.435o
d = 1500.0 111 5.0000 seconds after the target is dropped. On your way to showing this, ﬁnd the initial velocity of the cannon ball at the ﬁring time, and target dropped r V
at t = 0.000 sec : ‘ h:1112.5m (Show additional work on the next page if you need more space.) \J‘X T: datum omitssat) 5
xi}: \SOM/S a m, ' \rswo: 1. 4
\Fi = BOW/i2,
Initial X velocity of cannon ball : _ Initial Y velocity of cannon ball == Time of collision with the target = “(or indies? Cittap; D
 =7
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l loou Part C. (64 points total)
Show all work to receive full credit. 1. (2] points total) A 0.05 kg mass is held at rest against a spring with spring constant, k = 200
me which is compressed 0.2 m from its equilibrium point. The mass is then released and
moves along a track which is shown below. The frictional force between the can and the track is
30 small that it can be ignored at all points except between points F and G where there is a
frictional force present. The spring acts on the mass between points A and B. A) (4 points) Circle all regions in the list below in which the total mechanical energy ofthe
(spring—cantrackearth) system is conserved. Nowhere Everywhere, Energy is ALWAYS conserved ..,_ B) ('7 points) What is the velocity of the cart at point B? KL. (Emmett—Hon oi; ‘QVDJ‘H A +9 E'
AKE + : Wale f \F‘ 2: % (“lgkx ams‘v‘.) 3/.
_ lax“ ff"
V4 " "—— . Q \r‘ ”
Cho:£)( o :3“); / ocity : m : m ' ‘ 2(q_%\r~/SQ>C5m> units 0. o 5 k
C) (10 points) Assoda was spilled on the track between point F and 90th G, so that there is a
frictional force between the mass and the track in this region of 0.5 N. Point G is the highest
point that the cart reaches on the last hill. What is the height of point G under these conditions? (This height is represented by the ? in the diagram)
. J; A + o G
_' Coﬁ°s€rrxt Grit—\Oh GE. “O M K... AAKJ :‘U‘JML
(ks;  KEL) + (on% 4);) WM“; : \FQHCHCOEG (o — o)+(m3H — é; kx’") =L'.:F_4Gi C038” \xva
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imam“ ka  " 45 mad? ‘t‘eafcangiﬁs. “1
Height2 3\SL\' “h i: : O. 5 N g kx 15 ‘ units {
H — “Gym/Lose ' ~ (ESBCaoohCOQQ)
_._\‘\= 0.05t9.ei)+ 0.5/50330 \tt: 3.1557 my ...
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This note was uploaded on 04/28/2008 for the course PHYSICS 8A taught by Professor Jacobsen during the Spring '07 term at University of California, Berkeley.
 Spring '07
 JACOBSEN
 Physics

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