Midterm1ReviewSolutions

# Midterm1ReviewSolutions - Part C — Extended Problems —...

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Unformatted text preview: Part C — Extended Problems — 88 Points Total C-l ([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 ‘ i. \M O 1.0. a ,7 _ A \/ r. -1 >ng t \Ng — wO.ElO‘-"T:) - . _3. .- n ﬁrms“ Ash? * N? er 1 . [— ' a- L (moo ‘5 “0 0”“) “now units “1 3! [3f] point-:3 Stalin: Friefiun. H's black Milt mass M. rash; rm a ramp. which is at an angle u? it'1"ab0'.u-1hl: huriltmLuL I"; wanna Muck l‘if mas-s XL is wap‘endeé hy .1 "we 12ml tn the aim himL ims :‘ueﬂicwn: (121mm:- liicmm Eh: Mack i is; 1:3 nj, ._ .. _ and assume that 1hr: puile} am! rape am: lhcmminb and .ilinl'ﬁrﬂwﬁ. Hm [15“:th are n-m mswmg m ldt‘ntiiy ai'l lilacs :lciing an the (ma! hir'zc’x by [ﬁmnntg sum ult‘at‘ig' iahﬁmg 1:. I151.) M243. diagram. b': Draw and view-13’ fasﬁc‘i :1 Sim: {Ed} diagram Em: the scwnd Much. "£3 if M- ‘- 1.5 Lg. what 5:; 1f": magﬁimde- of the was-jun, 'i'. in the amt? d? m "mucus-.1. what 151m; smaiiezﬂ rah»: ill-ill M; mm 2-9.: wi-iimw: causigzg Hock f ls: Slill'l' gliding: up the mnp'? Q9 ‘L 1 YT I 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 omits-sat) 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? Cit-tap; D - =7 . “Rye: t: 1- %y t ' I ‘ rw ' \‘E {SW}: é (Eclng /<_,3‘>Lli'5'sd: j H‘— - G‘J‘ erf‘ﬁE. OJ; cz-\\‘-§\§J\r\ ﬂ . a ,3 . 39+ J_,__ \Om ” ‘f‘a a AX :‘ksxx't *Q—Oxt‘ 1‘3 OO‘OM : P501". t : \OS MVP“); " '55 t _ 52 -+c:+n\ ' v55 \50 m/s '50 mfs l5 5 £0:- Cgt-‘ﬁDh ‘30“- : L q». t? y t are a ,. + JH'me l t \O m a . ‘ Cannon L“ 04i- coili'ito-n l loo-u 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—can-track-earth) 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 .L a _ ﬁt: i bl imam“ ka - " 45 mad? ‘t‘eafcangiﬁs. “1 Height2 3-\SL\' “h i: : O. 5 N g kx 15 ‘ units {- H — “Gym/Lose ' ~- (ESBCaoohCO-QQ) _._\‘\= 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.

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Midterm1ReviewSolutions - Part C — Extended Problems —...

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