Inquiry an Communicaion 8. (a) ensiy eermine by Group A is he mos reasonable. (b) When roune off o wo significan igis, Group B has he same alue as Group A. Howeer, saing an experimenal measuremen o six significan igis oes no make sense. Group C is he only group wih a ensiy greaer han.0 g/ml. Likely heir alue is he reciprocal of wha i shoul be. Group D has he same basic numerical alue as Groups A an B, bu heir alue woul be he ensiy of a gas. Likely hey mean o wrie 0.7 g/ml. 9. To eermine elociy, boh he isance raelle an he ime ineral o rael ha isance are neee. se measuremens can be eermine using a meric measuring ape an a sopwach as he jogger runs from one marke posiion o anoher. n elociy isance. ime 0. (a) moion is occurring a a consan elociy because in each.0 s ime ineral he isance coere is 4.0 m. (b) See he graph below. (c) Seeral ses of aa poins can be use o calculae he elociy. One example is: isance spee ime 4.0 m.0 s spee 4.0 m/s CHAPTER MOTION Try This Aciiy: Comparing Velociies (Page 5) (a) Answers may ary, bu a ypical arrangemen wih esimae alues is: D: 0 000 km/h, B: 000 km/h, A: 0 km/h, C: km/h (b) A: 3 km/h; B: 8.5 0 2 km/h; C:.0 km/h; D:.38 0 4 km/h (c) Answers will epen on he preicions. To improe skills of esimaing aerage elociies, suens coul learn more abou approximae isances beween places (on maps or a globe), learn he approximae range of elociies of arious ehicles, an pracise arious esimaions.. MOTION IN OUR LIVES (Pages 8). (a) rubber sopper is acceleraing uner graiy as i falls. (c) rocke mus accelerae from res while rising from he launch pa. () moorcycle slows (eceleraes) as he brakes are applie, bringing he moorcycle o res. 2. (a) 2 ms, (b) 500 MHz, (e) 5 cm 2, (f) 50 ml are all scalar quaniies. None of hese hae irecions associae wih hem. 3. (a) scalar quaniies: elociy, isance, ime, mass, grae (inclinaion), frequency, area (b) oher scalar quaniies: olume, elecrical curren, soun inensiy, luminosiy 2 Uni Forces an Moion Copyrigh 2002 Nelson Thomson Learning
4. isance from he equaor o he geographic Norh Pole (illion meres) is imprecise because he exac locaion of hese posiions canno be known o absolue precision (an may change slighly wih ime). secon, as originally efine (8 400 s for Earh o roae once on is own axis), changes oer he course of ime. lengh of he ay is no consan ue o he graiaional rag he Sun places on Earh, slowing is roaion. 5. Surface area is measure in m 2, erie from meres meres; olume is measure in m 3, erie from meres meres meres.. 42.2 4.22 0 4 m 3 h 53 min 7 s a 3(300 s) + 53(0 s) + 7 s 4 4.22 3 997 s a? 3 997 s 3.0 m/s 3.0 m 3.0 0 3 km.0s 300h 3.0 m / s 3.0 0 3 km 300 h 0.9 km / h aerage elociy is 3.0 m/s or 0.9 km/h. 7. 38 cm 0.38 m a.9 0 7 s 0.38m a? 7.9 0 s a 2.0 /s aerage elociy of he elecrons is 2.0 0 m/s. 8. a (), a 9. 3.8 0 5 m a 9.5 0 3 m/s a? 5 3.8 3 9.5 /s 7 4.0 0 s a 2.5 s a 480 m/s? a () 480 m/s(2.5 s).2 0 3 m 800 m a 24 m/s? 0. a 28 cm/s 0.20 s? a 800 m 24 m/s 75 s a () 28 cm/s (0.20 s) 5. cm Bloo will rael a isance of 5. cm in he aora in 0.20 s. Copyrigh 2002 Nelson Thomson Learning Chaper Moion 3
. a. 0 3 km/h 2πr 2(3.4)(.5 0 3 a km) 4.08 0 4 4 km 4.08 0 km 3?. 0 km/h 2h I will ake 2 h o complee he rip. Aciiy.. Calibraing a Ticker-Tape Timer (Page 0) Analysis (a) Mos imers operae a a frequency of 0.0 Hz, which correspons o a perio of 0.07 s. Suens resuls shoul be expresse o wo significan igis an are accepable if hey are wihin abou 5% of he accepe alues. (b) Answers will epen on he calculae alues. (c) major source of error in his aciiy is human reacion ime. suen operaing he sopwach will hae a ifficul ime saring an sopping he wach a he exac insans require. Anoher major source of error is he oerlapping of os a he sar of he moion where a few os may be ifficul or impossible o isinguish. Ye anoher source of error coul occur if he imer is no working properly; i coul be ouble oing or skipping os. (Page 0) 2. (a) f 0.0 Hz T? T f 0 Hz 2 T.7 0 s perio of he spark imer is.7 0 2 s. (b) f 30.0 Hz T? T f 30.0 Hz 2 T 3.33 0 s perio of he spark imer is 3.33 0 2 s. 3. T 0.0 s f? f T 0.0s f.0 0 Hz frequency of he spark imer is.0 0 Hz. 4 Uni Forces an Moion Copyrigh 2002 Nelson Thomson Learning
Secion. Quesions (Page ). 3.9 km + 80.2 km + 42.2 km 22.3 km (2.23 0 5 m) 8 h 7 min 7 s 8 h (300 s/h) + 7 min (0 s/min) + 7 s 29 837 s a? a (.0 m/s 3. km/h) winner s aerage elociy was 7.584 m/s or 27.30 km/h. 2. (a) 3.00 0 8 m/s (elociy of ligh).00 s? a 5 2.23 29 837 s 7.584m/s 27.30 km/h a () 3.00 0 8 m/s (.00 s) 3.00 0 8 m Ligh raels a isance of 3.0 0 8 m in a ime of.00 s. (b) 3.00 0 8 m/s a ().00 ms 3.00 0 8 m/s(.00 0 3 s).00 0 3 s 3.00 0 5 m. Ligh raels a isance of 3.00 0 5 m in a ime of.00 ms. 3. Esimae isance: 5.0 0 3 km 5.0 0 m Esimae aerage walking elociy: a.5 m/s a? 5.0.5 m/s 3.3 0 s 38 Walking non-sop, i woul ake abou 38 o walk across Canaa. Applying Inquiry Skills 4. (a) One coul measure he isance raelle by he ip of he golf club as i moes hrough he arc. This is he alue of. By couning he number of separae images an knowing he perio of he sroboscope s flash, he oal ime for he swing is eermine by he number of inerals (number of images minus one) muliplie by he perio of he sroboscope. This is he alue of. aerage elociy is calculae by using he equaion a. (b) slowes insananeous elociy occurs when he isance beween successie images is he leas. fases insananeous elociy occurs when his isance is he greaes (as he club is sriking he ball). In boh cases, he elociies can be calculae using a, where isance raelle an ime aken (perio of srobe). 5. (a) 38 os represen 37 complee ibraions (cycles). ime ineral is 2.50 s. 37 frequency: f 54.8 Hz 2.50s (b) measure frequency: 54.8 Hz; rue frequency: 0.0 Hz experimenal accepe % error 00 accepe 54.8 Hz 0.0 Hz 00 0.0 Hz % error 8.7% experimenal error is 8.7%. Copyrigh 2002 Nelson Thomson Learning Chaper Moion 5
Making Connecions. car s oomeer measures he isance raelle. Is speeomeer measures he insananeous elociy. 7. Sign () is he bes because i inicaes he maximum allowe elociy (as oppose o a possible inerpreaion of elociy as aerage elociy). Secon, he uni of km/h is proper SI form. uni kph is no recognize an he elociy of 0 omis unis compleely..2 UNIFORM MOTION (Pages 2 4). An objec ha falls sraigh own experiences linear moion bu no uniform moion because i is acceleraing as i falls. 2. 2. m [S] 2 2 9.7 m [S] 9.7 m [S] 2. m [S]? 7. m [S] curling rock s isplacemen is 7. m [S]. 3. 2.8 m [W] 2 2 2. m [E] 2. m [E] 2.8 m [W]? 5.4 m [E] og s require isplacemen is 5.4 m [E]. 4. (a) 0.0 m 2 2 4.4 m [fw] 4.4 m [fw] 0.0 m? 4.4 m [fw] (b) 4.4 m [fw] 2 2 8.8 m [fw] 8.8 m [fw] 4.4 m [fw]? 4.4 m [fw] (c) 4.4 m [fw] 2 2 3.2 m [fw] 3.2 m [fw] 4.4 m [fw]? 8.8 m [fw] 5. y are he same.. 50.0 m [fw].9 s a a? 50.0 m [fw].9s a 2.9 m/s [fw] ahlee s aerage elociy was 2.9 m/s [fw]. 7. a ( ), a 8. a 2.4 mm/s [fw] a ( ) 40 s 2.4 mm/s [fw](40 s)? 3.4 0 2 mm [fw] 34 cm [fw] snail s isplacemen was 34 cm [fw]. 9. a 20.8 m/s [fw] (assume) 78 m [fw]? I woul ake he recor holer 8.5 s. a 78 m [fw] 20.8 m/s [fw] 8.5 s Uni Forces an Moion Copyrigh 2002 Nelson Thomson Learning