lee2 - 1 Calculate the net torque about point 0 for the two...

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Unformatted text preview: 1. Calculate the net torque about point 0 for the two forces shown in the figure. The rod and both forces are in the plane of the page. Take positive torques to be counterclockwise. ) N p2,: :10 N F, :81“) N a 12 -m b) ~12 N-m i C 28 Nm . ..i . n. .. Cl) ‘28 0 Mamas. hi. Jam (£22, «3 .. e) _52 Nm lea. (inhale—3.00 m ~94 73H 1\\1.,9m3c> ~ 5.8 : i \ ’L - Ho 2 - 18 N .m An artist constructs the perfectly—balanced mobile shown. If the artist decides to make the star twice as massive, and not change the length of any crossbar or the location of any object, what does she have to do with the mass of the smiley face to keep the mobile in perfect balance? Note that she may have to change masses of other objects to keep the entire structure balanced. ' a) make it eight times more mas— sive b) make it four times more mas- sive c) make it two times more mas- sive ' d) not ing e) impossible to tell Smog, 3&9 Ma‘s-r3 $5126; ngw‘tl AH Masgbs “495+ Chow» a 44ft. San/s2. QQO+DF\ 3. The flywheel of an engine has ome of inertia 3.0 kg-m2 about its rotation axis. What constant torque is required to bring it up to an angular speed of 10 rad/s in 10 3, starting from rest? a) 1-5 N'm N L d 3 N-m 1’ x c -m . d) BUN-m a" w 5 —_ Hulls?“ e) 150 N-m \O 5 2) t: 3-L =3W‘ A 1.0 kg solid disc 0.5 m in radius is rolling Without slipping on a horizontal floor at a steady 2 rad/ s. What is the total kinetic energy of the disc? a) 0.5 J K11:ka :. 14%”: 4. K macaw. m -. - t . vsw c 1.0 ._ fl ' - J z ‘iwvl 4- £12902 d) 1.251 ,, L .L l .3. mrz- w?- _e)..1.5.J ' ' ‘ * M” r 4‘ 2’ l. L .. i. 2. ’2 - 3 . g , — Smash 211nm —q:r ' A hoop, s‘olid disc, and solid ball start from rest at the same height and roll Without slipping down the left part of the track shown. The right part of the track is frictionless. Which object goes highest up the right side? a) hoop b soli ' d) all of them climb to the same -' ~’ “ti-7"" e) it is impossible to determine ‘ , 4,52”). {‘09 Without knowing their diame— . 0170/; WW» “fl «‘9 ters . - ‘ ‘ '1 "Th; object-F Wat’s 8°e5 \«xgl‘es’r \3 Thu cm W‘H” W‘— "‘05" Jrvmuas \q+,;,m| / lefxs+ «Din-hm\ \uvig-Hc amevw CU- bo-Hevw, 90 K H- 15 +kL w H" H -} 5—5 053 W - A small (point—like blocl‘c on aflfrfctign‘ltgssffiorizfocnta‘l surfalclet has almgs§ mler‘ha / max ' of' 1 kg. It is attached to a massless cord passing through a hole in the 'sUrface, as shoWn. The block at firstYr'eVolves at a distance of 0.3 m from I the hole with an angular speed 'of 1 rad/s. The cord is pulled from below, shortening the radius of the circle in which the block revolves to 0.15 m. What is the. new angular speed? 13; I m rs; a) 1 rad/s " b) 2 rad/s 1 rad {S l .B d 8 rad/s 7. 10. A circular steel wire 2 m long must stretch no more than 0.3 cm when a tensile force of 500 N is applied to each end of the wire. What minimum diameter is required for the wire? Young’s modulus for steel is 2x 1011 Pa. a) 7.3><10‘.~4 m. I {52‘ (bl l.§6><10,“:m) ' [1;1' ATV ) 2.05X10~ m .I ' ' C d) 2.91x10“3 m e) .4.61x10”3m " —~— :: : ZJMQ' - "NW W -3x W3. 2M0“ Far from the Sun (R z 00), a spacecraft is out of fuel and its kinetic energy 01 = lu‘féfio'} is zero. If only the gravitational force of the Sun were to act on it (neglect v other solar system objects) the spacecraft would eventually crash into the Sun. The mass of the Sun is 2x1030 kg and its radius is 7X 108 In. Find the speed of the spacecraft when it crashes into the Sun. a) 8.0x103m19 ~§-T+Ut= 0“ 0‘0 b) 1.2x104m15 ._ AWVI- c) 3.4x104mU E? In“ ‘ 2' d 7.8x104mIS ., “(mm m ..u 30 1’2 _ (e) 6.2x10f "b v ‘ 1-: :2 7‘ L‘ X“) ‘ 2ND ‘ z Lam:va . . ., . . 7-105. .. . 5 Rhea, one of Saturn’s moons, has a radius of 8X105 m and an acceleration duetto gravity of.O-.3 m/sz at its. surface. At what distance above Rheas surface is the acceleration due to gravity 0.1 m/s2? ww‘zo r i 2. 2. ' a) 0.6x106m 81 GE 50 g” 2 f_ or y": 91 fiflfsmfi 1.1><10 m «*1 a p?- 3‘ ” T c) 1.4X106m d) 1.8x106m r‘: Cir :2. LC???» 91405 = 1.3¢<¥ID‘M e) 3.0X106m “MW = Q3“)? 2032- e~no5= aaxiosm The acceleration due to gravity at the north pole of a planet is 10 m/sz. The planet has radius 25x106 m. The apparent weight of objects at the planets equator is zero. What is the rotational angular frequency of the planet? r , a) 3.8x10‘4 rad/s W appumwfia 0 =5 OlajccA-s “fin or‘oT-lr" b 4.1x10’”4 rad/s (c) 6.3x10”4 rad/s5 or -CC, 1 d 8.7X10'” ra s a _ A V "’ 3 e) 1.2x10~3 rad/s '/ - Z =.L3N° 3% 11. Consider a steady laminar flow of incompressible water (p = 1000 kg/m3) in the horizontal pipe shown with changing cross—sectional area. Area 1 is 2 m2, area 2 is 0.5 m2, and the flow speed at point A is 1 m/s. Find the pressure change from point A to B (PB —— PA). a) 1.5><103 Pa b) ~1.5><103 Pa c) 7.5X103 Pa W 9’7“ “‘°°“‘3 \th 1 - e 1. X1 a P Lbfl‘l'mvora A‘VA2A1UB fi‘ V9: ANA-2 iii ; HIM/5 Area 1 YE—Pa = % {)(VAl-fl/ga) ____‘ 5 : a‘wobC‘1_HQ 2 $7530 P4 12. Consider tfifld‘following statement: The magnitude of the buoyant force is equal to the weight of the amount of fluid that has the same total volume as the object. Under what circumstances is this statement true? 1r 1; a W 9va \g \E a) for an object that is partially submerged in a fluid b) only for an object that floats :5 Vglv‘é) : VDESECAP c or an object completely submerged in a fluid r.) Dyiec'l‘ ample‘ctla d) or no oJec par 1a y or comp - - y sumerged in a fluid 5 m b wwgal e) none of the above 13. A flask of water rests on a scale weighs 100 N. A small block attached to a rod is then completely submerged in the water. The block does not touch any part of the flask, and the person holding the block will not tell you whether the block is being pulled up (keeping it from falling further) or pushed down (keeping it from bobbing back up). What does the scale read now? ~ move cag¢k 1 pm (rpm/GU 'l’poske; Hr down W 59 F9 =Wwakt'lwblwlI—l-T 3' wwwe'x Cage 11 flbPVWOAf/W “T :0 Q9 1 meerJrl/Ubloclc. >qu 100 N between 0 N and 100 N ) ) ) less than 0 N ) it is impossible to determine. 'T’ "Yard-[ab Sup port; lalodz E 1” ,s, E; 1 W b\oL\’\ S:‘s “— WWW-kw Arm/moan —T 3 wwalér so $5 02le35 b WWakr 1(OOH 14. 15. An ice cube floats in a glass filled to the top With water. What happens when the ice cube melts? a The water overflows. c) The water level decreases. d) To answer the question, one needs to know the area of the glass and ice volume. e) It is impossible to determine. An evacuated bell jar is separated from the base plate by a rubber gasket, . as shown. What is'the total force bearing down on the. gasket if. the outer radius of the bell jar R is 0.1 In, and the gaskets Width} w is much smaller than~_R?. Neglect the weight of the glass; atmOsphericpressure is_'1>05 Pa." M a) 79x102N basket b) 16x103N c) 2.4x103N Ed) 3.1x103 N 7 e 4.7x103N U5) g : p . A TCe/ Cqbc vol/16M «Mafia grefzfié/ ft 905$ \eyg dwéc)‘ Q»? \o awffiuvkg ) \kasv (JL‘SQlClunr, 5mm. Welghvog 0M WQAY€( :> “9&1er \evd m3 2:» : WWW ‘7 ' , . l SWU 1 \Dbf’W ‘ (3‘0 ~ (/0044 watt-22K . - 09 . " MW ' ...
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lee2 - 1 Calculate the net torque about point 0 for the two...

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