LAB 3: VELOCITY AND ACCELERATION GRAPHS

Transcription

1 Goas: LAB 3: ELOCITY AND ACCELERATION GRAPHS Invstigat accration vs. tim graphs Prdict accration graphs from vocity graphs Invstigat accration as sop of vocity vs. tim graph Part 1 - Making ocity- Graphs Priminary activitis 1. Prpar quipmnt. Connct th motion snsor to th Xporr GLX, and thn to your aptop. It woud b vry hpfu to ook at th onin hp pag for this ab. Start th DataStudio softwar. 2. Load th xprimnt fi. Load th DataStudio fi Lab03_ocityGraphs.ds from th Physics1 fodr. 3. Prpar program for graphing. Mak sur th graph ayout is st to dispay on graph - ocity vs.. [S th graph ayout hp pag for graphing information in DataStudio.] 4. Starting th graphing procss. Whn you ar rady to start graphing, cick th START button in th midd of th toobar. W wi now mak spcific vocity-tim graphs to ook at changs in waking spd and dirction of motion. This is an important sction, bcaus it conncts th motion with how it is dispayd. A) Accrating away. Start at 50 cm from th dtctor, and wak away from th dtctor with your spd incrasing stadiy. Draw th graph on th Data/Qustion shts. B) Dcrating away. Start at 50 cm from th dtctor, and bgin to wak away quicky and thn sow down and stop (spd dcrasing stadiy). Draw th graph on th Data/Qustion shts. C) Accrating toward. Start at 2 m from th dtctor, and wak toward th dtctor with a spd that incrass stadiy. Draw th graph on th Data/Qustion shts. D) Dcrating toward. Start at 2 m from th dtctor, and wak toward th dtctor quicky at first and thn sow down stadiy and stop (vocity dcrasing stadiy). Draw th graph on th Data/Qustion shts. Part 2 - Prdicting ocity - Graphs Whn finishd with ths, stay with th Data/Qustion Shts for th foowing sction. Rfr to th Data/Qustion Sht for this sction. Part 3 - Matching an Existing ocity- Graphs In this activity you wi match a vocity graph shown on th computr scrn. Rv 09/16/08 Copyright Scott Schnidr Lab 3 ocity and Accration Graphs - Pag 1 of 8

2 1. Opn samp fi. Opn th Lab03_ocityMatch.ds fi. Th vocity graph to th right wi appar on th scrn. 2. Car any od data. Us Dt A Data Runs from th Exprimnt mnu if ncssary. Figur 1 ocity matching curv 3. Prpar to match that curv. Cick START and mov to match th vocity graph shown on th computr scrn. You shoud try to dupicat th faturs of th ocity Match graph. You may try a numbr of tims. Work as a tam. Try to match th tims and spds -- it woud hp to ook at th computr scrn as you undrgo th motion. Each prson shoud tak a turn. Qustion Answr on th Data/Qustion Shts. What was th diffrnc in th way you movd to produc th two diffrnty sopd parts (in th first part) of th graph you just matchd? What about th sop at th nd of th graph? SAE this data st (your matching st) on your computr, undr a nw nam. Part 4 Statistics of th Motion 1. Estimating th avrag accration. Using th SMART TOOL, cick in th accration graph, and thn sct a rgion of th accration graph whr th accration is rasonaby constant (or supposd to b). Thn us th summation too to dispay th MEAN vau (basicay avraging ALL th points in your sction), th information wi show up in th gnd. Rcord th man accration on th Data/Qustion shts. [Thr is information about how to us th summation too in th stor and xamin hp pag.] Qustion Answr on th Data/Qustion sht. How dos th magnitud of th man accration for your motion compar to th vau from th match for that sam rgion? (If your vocity curv is roughy simiar to th vocity match curv, th accration vaus shoud b simiar.) Expain your answr. Part 5 Accration Graphs - Cart on a ramp W hav xprincd our own human-powrd vocity and accration curvs, but it is difficut to maintain a stady accration. For a constant accration, w wi turn to an incind track and a cart that ros up and down on it. 1. Prparation. St th motion dtctor on th top nd of th track, campd on. Us th po and camp at th nd of th track to rais on nd--start with a ow tit to th track (about 4-5 cm from th tab). Whn you start th cart, mak sur it is at ast 0.5 mtrs from th dtctor. Load th fi Lab03_CartTrack.ds fi. Mak sur th tim axis is st to at ast 5 sconds. Rv 09/16/08 Copyright Scott Schnidr Lab 3 ocity and Accration Graphs - Pag 2 of 8

3 2. Graphing th cart roing down th ramp and spding up. Lt th cart start from rst (0.5 mtrs from th snsor). Cick START and thn ras th cart whn th cicking sound starts. Mak sur that th program is graphing bfor you t go of th cart. (Aso, mak sur th dtctor dosn t s your hands.) 3. Stor graphs. Your goa is to find a nic smooth graph of th motion. This mans th vocity graph shoud hav a straight-in rgion, and th accration shoud hav a smooth horizonta rgion. Whn you hav a nic can curv, nam thm (such as ow tit ). 4. Highr tit to track. Incras th tit of th track a itt (a fw mor cntimtrs highr at th far nd). Prform th xprimnt again unti you gt a can curv. Nam this data aso (namd high tit?). Low Tit Graph 5. Finding th avrag accration of th cart from your accration graph. Undr th Data mnu on th graph, hid th high tit run (so ony th ow tit run is visib). Locat a rgion of th ow tit graph whr th accration is rasonaby constant (a horizonta sction of th accration curv, or a straight-in portion of th vocity curv). Using th SMART TOOL, idntify about 10 vaus (roughy quay spacd in tim) of th accration. (Ony us vaus from th portion of th graph aftr th cart was rasd and bfor it hit th nd of th track -- during th constant accration rgion.) Rcord ths numbrs on th Data/Qustion sht, and thn cacuat th avrag vau of th accration. 6. Finding th avrag accration from your vocity graph. You wi cacuat th sop of your vocity graph (which shoud b th avrag accration ovr that intrva). Using th SMART TOOL, rad th vocity and tim coordinats for two typica points on th vocity graph. For a mor accurat answr, us two points as far apart in tim as possib but sti during th tim th cart was spding up (it shoud b during th straight-in portion of th vocity graph. Rcord ths vaus on th Data/Qustion sht. 7. Find th sop (th avrag accration). Cacuat th chang in vocity btwn thos two chosn ndpoints. Aso cacuat th corrsponding chang in tim (tim intrva). Divid th chang in vocity by th chang in tim. This is th avrag accration. Show your cacuations on th Data/Qustion sht. 8. Cacuating th man accration. Cick in th Accration graph, and using th SMART TOOL sct a rgion of th accration graph whr th accration is constant (basicay th sam ara from which you took th 10 points). Using th summation mnu on th graph dispay th MEAN vau for that datarun. Rcord th man accration of that ow tit sction on th Data/Qustion sht. Qustions Answr ths qustions on th Data/Qustion sht. a) Is th accration positiv or ngativ? Is this what you xpctd? (Expain your answrs.) b) Dos th avrag accration you just cacuatd agr with th avrag accration you cacuatd from th accration graph? Do you xpct thm to agr? How woud you account for any diffrncs? (Expain your answrs.) Rv 09/16/08 Copyright Scott Schnidr Lab 3 ocity and Accration Graphs - Pag 3 of 8

4 High Tit Graph 9. Find th avrag accration of th cart from your accration graph. Hid th ow tit run and SHOW th high tit run. Using th SMART TOOL, find 10 vaus during th constant accration rgion. Thn cacuat th avrag vau of th accration on th Data/Qustion sht. 10. Finding th avrag accration from your vocity graph. Cacuat th sop of your vocity graph. Using th SMART TOOL, rad th vocity and tim coordinats for two typica points. Rmmbr to us two points as far apart in tim as possib. Rcord ths on th Data/Qustion sht. 11. Cacuat th avrag accration. Foowing th stps in Part 5.7, cacuat th avrag accration for th high tit portion of th graph. 12. Cacuating th man accration. Foowing th stps in Part 5.8, cacuat th man accration for th high tit portion of th graph. Rcord th man accration on th Data/Qustion sht. Qustions Answr on th Data/Qustion sht. a) Dos th avrag accration cacuatd from vocitis and tims agr with th avrag accration you cacuatd from th accration graph, and th man accration from th program? How woud you account for any diffrncs? (Expain your answrs.) b) Compar this avrag accration to that with th Low Tit. Which is argr? Is this what you xpctd? (Expain your answrs.) 13. Print th High/Low graph. Show both runs (ow and high), and print th graph from this sction to incud with your ab rport. (S th printing with DataStudio hp pag for assistanc.) Rv 09/16/08 Copyright Scott Schnidr Lab 3 ocity and Accration Graphs - Pag 4 of 8

5 DATA/QUESTION SHEET FOR LAB 3: ELOCITY AND ACCELERATION GRAPHS Part 1 - Making ocity- Graphs 2. Accrating away. Start at 50 cm from th dtctor, and wak away from th dtctor with your spd incrasing stadiy. (sc) 3. Dcrating away. Start at 50 cm from th dtctor, and bgin to wak away quicky and thn sow down and stop (spd dcrasing stadiy). (sc) 4. Accrating toward. Start at 2 m from th dtctor, and wak toward th dtctor with a spd that incrass stadiy. (sc) 5. Dcrating toward. Start at 2 m from th dtctor, and wak toward th dtctor quicky at first and thn sow down stadiy and stop (vocity dcrasing stadiy). (sc) Part 2 - Prdicting ocity- Graphs Prdiction Prdict th graph producd whn a prson starts at th 0.5-mtr mark, accrats away from th dtctor stadiy (spd incrass) for 4 sconds, thn sows down for 6 sconds (dcration with a smar magnitud than th accration) and stops and thn accrats toward th dtctor. Draw your prdiction on th ft axs bow using a dottd in. Rv 09/16/08 Copyright Scott Schnidr Lab 3 ocity and Accration Graphs - Pag 5 of 8

6 Compar prdictions with th rst of your group. S if you a agr. Draw your group's prdiction on th ft hand axs using a soid in. (Do not ras your origina prdiction.) Writ th prdiction bfor prforming th xprimnt. PREDICTION RESULT 1. Do th xprimnt. Mov in th way dscribd and graph your motion. Whn you ar satisfid with your graph, draw your group's fina rsut on th right axs. Qustion If th fina rsuts diffrd from th prdiction, xpain why. If th fina rsut is th sam, xpain th charactristics of th graph and why you chos thm. Part 3 - Matching an Existing ocity- Graphs Qustion Answr on th Data/Qustion Shts. What was th diffrnc in th way you movd to produc th two diffrnty sopd parts (in th first part) of th graph you just matchd? What about th sop at th nd of th graph? Part 4 Statistics of th Motion Man Accration from your motion = Man Accration from match = Qustion How dos th magnitud of th man accration for your motion compar to th vau from th match for that sam rgion? (If your vocity curv is roughy simiar to th vocity match curv, th accration vaus shoud b simiar.) Expain your answr. Rv 09/16/08 Copyright Scott Schnidr Lab 3 ocity and Accration Graphs - Pag 6 of 8

7 Part 5 Accration Graphs - Cart on a ramp Low Tit Graph 5. Finding th avrag accration of th cart from your accration graph. (Ony us vaus from th portion of th graph aftr th cart was rasd and bfor it hit th nd of th track -- during th constant accration rgion.) Accrations from graph (m/sc 2 ): (Ths shoud vry simiar!) Avrag accration (man): m/sc 2 (Low Tit) 7. Find th sop (th avrag accration). Point 1 ocity m/sc Point 2 ocity m/sc Chang in vocity: m/sc sc sc intrva: sc Avrag accration: m/sc 2 (Low Tit) 8. Cacuating th man accration. Man accration = m/sc 2 Qustions a) Is th accration positiv or ngativ? Is this what you xpctd? (Expain your answr.) b) Dos th avrag accration you just cacuatd agr with th avrag accration you cacuatd from th accration graph? Do you xpct thm to agr? How woud you account for any diffrncs? (Expain your answr.) High Tit Graph 9. Finding th avrag accration of th cart from your accration graph. Accrations from graph (m/sc 2 ): (Ths shoud vry simiar!) Avrag accration (man): m/sc 2 (High Tit) Rv 09/16/08 Copyright Scott Schnidr Lab 3 ocity and Accration Graphs - Pag 7 of 8

8 10. Finding th avrag accration from your vocity graph. Point 1 ocity m/sc sc Point 2 ocity m/sc sc 11. Cacuat th avrag accration. Chang in vocity: m/sc intrva: sc Avrag accration: m/sc 2 (High Tit) 12. Cacuating th man accration. Man accration = m/sc 2 Qustions a) Dos th avrag accration cacuatd from vocitis and tims agr with th avrag accration you cacuatd from th accration graph, and th man accration from th program? How woud you account for any diffrncs? (Expain your answr.) b) Compar this avrag accration to that with th Low Tit. Which is argr? Is this what you xpctd? (Expain your answrs.) How do I writ up this ab? What is rquird for this ab rport? Consut th Rubric for this xprimnt and th Lab Rport Instructions documnt (both found on th Lab Schdu pag).. Qustions/Suggstions -> Dr. Scott Schnidr - S_SCHNEIDER@LTU.EDU Portions of this aboratory manua hav bn adaptd from matrias originay dvopd by Priscia Laws, David Sokooff and Ronad Thornton for th Toos for Scintific Thinking, Ra Physics and Workshop Physics curricua. You ar fr to us (and modify) this aboratory manua ony for non-commrcia ducationa uss. Rv 09/16/08 Copyright Scott Schnidr Lab 3 ocity and Accration Graphs - Pag 8 of 8