補史名www asftrppfysfts 600) For Thoughtand Diseussion tneuish the Aristotelian and Galilean/Newtonian views ofihe ball bounees ofrawall with the same speedithad beforeithit Wall Has its momentum changed? Hasaforoe acted on the 2 Has aforee acted on the wall? Relate your answers to New aws of motion ten use the term "inertias to deseribe human sluggishness 5this usage related to the meaning ofFsinertiae in physics? does aceiling fan continue to rotate even after you have vitched it ofP? Wek erashes into a Stalled cear A student trying to explain the es ofthis event claims thar no forees are involved: the car Tin the way”so itgot hit Commen foot astronaut kicks a ball, hard, across aspace station balls apparent weightlessness mean he astronauts toes 下avity on Jupiters moon Io is one-fifth that on Would happen te your weight and to your mass if nIo? tis the direcetion of momentum oFamoving body? Does it Fthe body: plane aceelerates down the munway, you take your keys r poeket and suspend them by a thread. Do they hang force from the chairon you. iir? Hnot, what forees are fxerrisesaned Problems 85 $ 還2620Groeoeoeardaoeos WiA poaor Wonoeno0 Op ir oa 20。 Staring frorm rest and undergoing constan acceleratiom,a920-kg ar covers 410 min $.15 8. Find the foree on the car 21 dropping dontest, a student encatses am 83-g cgg in large Styrofoam block. fs g emn'texceed 2.0N and 計the bloek hits the g pow mueh must the Styror jompress on impaet) Note: The aceelei assoeialed with stOppi gravity while the Styrofe the ground. 22. Inatront-end collision, a 1400-kg car with shockzabsorbing bump: ems can withstand amaximum force of 75kN before damage Gccurs: Hthe maximum speed foranondamaging collision is 9.0 kmzh, by Bow much must he bumper be able to move relative to the car? section 4.4 The Force ofGravity 23。 Show that the units of aceeleration can be written as N/kg- Why doesitmake sense to give gas 9.8 N/kg when talking about imass and weight? 24. Your spaceship crashes on one of the Sun's planets, Fortunately 上 the ship's scales are intact and show that your weightis 680 N.H your mass is 58 kg, where are you? (imr: Consult AppendixEE) Your friend can barely lift a 35-kg concrete block on E: massive ablock could she lift on the Moon? 26 Acereal box says "net weight 350 grams” Whats the actual Weight ta in SLunits and (b) in ounees? 27. Youre asafety engineerforabridge spanning the U,S-Canadian border. U.S. speeifications permit a maximum load of 10 tons What load iimit should you speeify on the Canadian side. where welght is given in kilograms? 28.。 The gravitational acceleration atthe lntermational Space Stations altitude is about 91凶 oFits surface value. Whats the weightofa 64-kg astronaut atthis altitude? ection 4.5 Using Newton's SecondLaw A 50-kg parachutist deseends atasteady 40 km/h. What foree does air exert on the parachute? 30, A 960-kg motorboat accelerates away from adock at2.1 m/s Its propellerprovides a3.9-kN thrust force. What drag force does the water exert on the boat? An elevator aceelerates downward at2.4 ms. What force does the elevator's floor exertona52-kg passengery 32. At 560 metric tons, the Airbus A-380 is the World's largest air- liner Whats the upward force on an A-380 when the plane is (am flying at constant altitude and (b) aceelerating upward at 15m/s2? 33. Yourre an engineer working on Ares 1 NASAs replacement tor the space Shuttles. Performance speces call for afirst-stage TOcket Gapable ofaccelerating atotal mass 0f 600 Me vertically ftom Testt0 7700 km in 1.7 min. Youre asked to determine tbe re- quired engine thrust (force) and the foree exerted ona79-kg as- tronaut during Tiftoff. What do you Teport? 34. You step into an elevatorand itacceleratesto adownward speed gfF8.8 mAS in 2.4 5 Quantitatively compare your apparent weight during thistime with youracetual weight, 44.6 NewtonsThirdLaw ional foree does 3 5600-kg elephant exer 必 63. she jumps ofta140-emhi過台 人 rdheras she falls?
4 FOFCe ad Motion 蛻. 生 ym, Ff 1t5 spTIn喲 ing 48 retch a sprIn What foree is neceSsary to Stretch a 8PT 4 constantis 270 N/m7 38. A 35-N force is applied toa 三 260 N/m. How much does the 和 生 39. Aspring with spring constant 大 守 只的 6.7-kg fish. How fr does the sprInE Stretch: ~ ant ith spfing cos h7 used to weigh a Problems 9 ie 40. A 1.25-kg object is moving 呈 the direetion at 1 3.31 slater is moving at27.8 m/s at 32.07 to the共說一 pthis time- magnitude and direction ofthe force applied durlng 由 41. An airplane encounters sudden turbulence 1 70% of farily Jighter. IF your apparent weight seems to 說 全 your normal weight, what are the magnitude and direction o Plane's acceleration? 呈 42. A 70-kg tree surgeonridesa “cherry picker” 1ift to reach the up per branches ofa tree. What force does the lift exert On the sur- geon when its (a) atrest; (b) moving upward at a steady 2.3 m/S; (e) moving downward at a steady 2.3 m/S; (d) accelerating up- ward at 1.3 m/s-; (e) accelerating downward at 1.3 m/s2? 43. A daneer executes a vertical jump during which the floor pushes up on his feet with a foree 44% greater than his weight. What s his upward accejeration? 44. Fnd expressions for the force needed to bring an object of mass 中 Test to speedp(a) in time Aand (b) over distance A志 9 、 elevator mmoves upward at 5.9 m/s. Whats its minimum stop- 誠 Ping time 導向e passengers are to remain on the floor? AA 2.50-kg object IS moving 引ong the x-axis at 1.60 m/Ss. As passes 負e origin, two forces 吳: 台 人章 說間 1and /2 are applied, both 號負e y-direction (plus i 答@ P us Or minus). The forces are applied ff 3.00 5s, after which the object is atx 三 4.80 pplied for 五二15.07 N, whats 及? 還IT 12N FURE4.22 problem 47 Ch 0 Cu any frict zontal 4 first roP force Or 人 er FIGURE。 Abio To det spPTIng cage a An el betwe rope thec: fricti 人六 less 灶卅 Show edui