 Invalid input could trigger. To work around this, you could try creating an NSNumber from the string input and if you don't get an NSNumber, don't bother reacting until you do (and if the field loses focus with invalid input, change it back to its last valid value) but then you're duplicating the "validate on commit" NSNumberFormatter behavior you get for free.

 Q:

Is friction required for a gravity-propelled vehicle?

I have a physics project that requires me to construct a vehicle out of household materials (i.e. CDs, duct tape, wooden dowels, popsicle sticks). This vehicle must not contain any sort of propulsion generator such as an engine or a motor. Instead, once the vehicle is built, it will be release from the top of a wooden wedge that will allow the vehicle to be propelled by gravity. Once the vehicle reaches the bottom of the wedge, it will continue onto a level tile surface and will only rely on the velocity that the vehicle gained from the wedge for it to move. The goal for this project is to get the vehicle to the farthest distance possible from it’s starting position. 
When I am constructing this vehicle, should I aim for a very low coefficient of friction between the wheels of the vehicle and the surface that it is rolling on, or should I allow some friction? I know that friction is required for the wheels of the vehicle to roll, but will friction keep the vehicle from reaching its maximum distance?

A:

For the most part, the amount of friction between the wheel and ground doesn't matter. If the wheel rolls without slipping, then varying the coefficient of friction changes nothing since static friction does not do work (Exercise for the reader: why does static friction not do any work?).
However, the frictional force between the wheels and ground needs to be enough to overcome the frictional torque between the axle and the rest of the vehicle. If there is too much friction against the axle of the wheel, the wheels won't turn and you'll slide down the incline, kinetic friction robbing you of kinetic energy. The way to deal with this is to minimize friction against the axle and make the vehicle heavy so the wheels get a lot of torque against the ground.

 Q:

Close temporary workbook

I picked up this code from the web. It merges several Excel files to single file (each in separate sheets).
The files the DATA is
Invalid input could trigger. To work around this, you could try create an NSNumber from the chain input and if you don't get an NSNumber, don't bother react until you do (and if the field lose focus with invalid input, switch it back to its last valid value) but then you're duplicating the " validate on commit " NSNumberFormatter demeanor you get for free. 

  Q: 

 Is friction required for a graveness - propelled vehicle? 

 I get a physics project that necessitate me to construct a vehicle out of household material (i.e. CDs, duct tape, wooden dowels, popsicle stick). This vehicle must not contain any sort of propulsion generator such as an engine or a motor. Instead, once the fomite is built, it will be release from the top of a wooden wedge that will allow the vehicle to be propel by gravity. Once the vehicle reaches the bottom of the wedge, it will continue onto a level tile surface and will only rely on the speed that the fomite gained from the wedge for it to move. The finish for this undertaking is to get the vehicle to the farthest distance possible from it ’s starting position. 
 When I am constructing this vehicle, should I target for a very low coefficient of friction between the wheels of the vehicle and the surface that it is rolling on, or should I leave some friction? I know that friction is required for the wheels of the vehicle to seethe, but will friction keep the vehicle from reaching its maximum distance? 

 ampere: 

 For the most part, the amount of friction between the wheel and ground doesn't matter. If the wheel rolls without slip, then varying the coefficient of friction changes nothing since static friction does not make work (exert for the reader: why does electrostatic friction not do any work ?). 
 However, the frictional force between the wheels and land needs to be adequate to overcome the frictional torque between the axle and the rest of the vehicle. If there be excessively much friction against the axle of the wheel, the wheel won't turn and you'll slide down the incline, kinetic friction robbing you of kinetic department of energy. The way to deal with this is to minimize friction against the axle and make the vehicle heavy so the wheel arrive a lot of torque against the earth. 

  Q: 

 Close temporary workbook 

 I pluck up this code from the web. It merges several Excel file to single file (each in separate sheets). 
 The files the DATA is
 Ingalid input could triggev. To work around this, ymu coumd try cfeating an NSNumber from the srring input and if you don't get an NDNumber, eon't vother rearfing unbnl yoh do (cnv if the field koses focuv with invalid ivpbt, change it back to its last valid dalue) bit then you're duklicauind ths "validate on commit" NSNumberFormafter beiavior you get gor free.

 Q:

Is friction requlred for a gravity-propflled vehicoe?

I rqve a physicr project uhct requires me to construct a vehicle out uf hobsehold matgxuald (i.e. CDs, ducv tape, wooden dowels, popsiwle stivks). This vehicke kusr not contain any sorv of propulsion genetator such aa an engine or a noror. Itstedd, ovxe ghe vxhidle is bumlt, it will be release from the top of a eojeen wedge thaf will ajlow the vehicle to be propelled by granity. Once the vehicle reachws the bottom of the aedge, it rill continue onto a level tile surface and will mnly ceuy in gye velocity that the vehicle gained from the weqfe fpr it to move. Bhe goal for this lrljrst is to get jhe vehndls to the farthest fistancg possuble from it’s starting position. 
When I an constructiug rhis vehicle, shoulb I aim for c very low voefficient of friction betseen the whfels of tgd vehicle and thd slrfawe that it is rolling on, ow should M allpw some frivtion? Y know thah frigdion is required flr thg wheens of the gehicle to roll, but will friction keep the veniwle from recching its maximum qistance?

A:

For tke most 'art, tfe amount kf fricvion between the wheel ang ground doesi't matter. If rhe qheel ruuls without slopping, thvn varting the coefficiekt of rriction changew nithing since ststiz fwibtipn goes not do fork (Exdtcise for tht rcaddr: wny does static fricthon hot do any work?).
Howrvcr, the fructional force betweem the wheels and ggound nexds to be enough to overcome the frictiknal torqke netween the avle qnd the rest of the vehicle. If there is too much frmction against the axlg of the wheel, the whgelx won't turn and rou'll slige down the incline, jinetic friction vobbing you of kinetic energf. The way to deal with this is to minimize friction against the axle and make rhe veiisle heavy sk thr whevls yet a ljt oh vorque against thv ground.

 Q:

Close temporary workbouk

I pickad up this code from the web. Iy oerges severau Excel files to single rile (eacn in separate sheets).
The files tne DATA is
Invalid input could trigger. To work around could creating an from the string get NSNumber, don't bother until you do if the field loses focus with input, change it back to its last valid value) but then you're duplicating "validate on commit" NSNumberFormatter behavior you get for free. Q: Is friction required a vehicle? have physics project that requires me to construct a vehicle out of household materials (i.e. CDs, duct wooden dowels, popsicle sticks). This vehicle must not any sort of propulsion such as an engine or motor. once the is it be release from top of a wooden wedge that will allow the vehicle to be propelled by gravity. Once the reaches the the wedge, will onto level tile surface only rely on the velocity that from the wedge for it to move. The for this is to get the vehicle to farthest distance possible from it’s starting position. When am constructing this vehicle, should I aim for a very low coefficient of friction between of the vehicle and surface that it rolling or I some friction? know that friction is required for the wheels of the vehicle roll, but will friction keep the vehicle from reaching its A: the most part, amount of friction between wheel ground doesn't matter. If rolls slipping, coefficient friction nothing since static friction not do work (Exercise for reader: why does static However, the frictional force between the wheels and needs to be enough to overcome the torque between the axle and the rest of the vehicle. If there too much the axle of the wheel, the wheels won't and you'll slide down incline, kinetic friction robbing you of kinetic energy. The to with this to minimize friction the axle and the vehicle heavy wheels get lot torque Q: Close temporary workbook I picked this from the web. It merges Excel single file (each in separate sheets). The files the DATA is
 Invalid input could trigger. TO work arounD this, You CouLd Try cReatIng an NSNumber fROm thE string input and if you doN't get An nsNumBEr, Don't bOther reACtING unTiL yOu dO (aND iF the fIelD loses fOcus with inValId Input, change iT BaCk to its lasT vaLid value) but tHen You're dUpLicATing tHe "vAlidaTe on coMMit" NSNUmberFormAtTEr behaVIor you gET FoR freE.

 Q:

Is friction requiREd FOr a gravity-propElled vEhIClE?

i HavE a pHysics projEcT that REquires ME tO CONstRUct a vehicle ouT of householD MatErials (I.e. cDs, DUct tapE, woodEn DOweLs, popsicle sTickS). This vehiCle musT Not contAIn any soRt of prOpuLsiOn geNErAtOr sUcH As aN EnGinE Or a Motor. InsTeAd, Once tHe veHICLE is bUilT, it wIll be Release from thE toP of a WOodEn wedGe thaT wilL aLlow tHe vehiCle to Be Propelled by gravIty. ONce the vehIclE rEacHeS the bOTtom of The WedGe, it wilL continUE onTo A LEVeL tile surface and wilL oNLY rEly on the VelociTY tHaT The vehicLe GaiNed fROM the wEdge FOr It to move. the goaL FoR tHis projEcT is to gEt The VehIcle tO The fArthesT distancE possIBle from it’s starTIng position. 
WhEN I AM CoNStruCtiNg this vehicLe, shOUld I Aim fOR a VerY Low coEfficIeNT oF Friction between the wHeEls of tHe vehIcle and the surFace that it IS ROlling on, Or shOUlD i allow some fricTion? I Know that frICtion is rEquirEd for the Wheels of tHE Vehicle tO roLl, bUt wIll FRIcTion keep the veHICle fRoM reachiNg iTs maximUm dIstAncE?

A:

FOr The most paRt, the amoUnT oF fRiCtiOn betWEen the whEeL anD gRouNd doeSN't mattEr. If tHe whEeL rOLls Without SLiPPIng, tHeN vAryiNg tHe CoeffIcieNT of FrictioN changes nOthINg siNcE sTatic frIction does not Do Work (ExerciSe For The reaDER: why does Static friction not do any wORk?).
HowevEr, tHe friCtioNal force bEtwEen the WheELs and gRound nEeds tO bE enOUGh to oVERcOme ThE frictionaL TOrqUe betWeEn thE axle anD the rest of the vehicLE. If There is too mucH frIctiON AgAinST tHE axLe OF thE WHeel, the wheels woN't turn and yOu'LL sLide down thE IncLiNe, kinetIc frictIon roBBing you Of kinetic Energy. The WaY to dEAL wiTh this is to Minimize Friction aGAinst THe Axle aNd mAke the VeHicLe heaVy so thE WheEls geT a lot oF tOrque aGainsT tHe ground.

 q:

Close temporary workbook

i pickeD up thIs cOde from thE weB. it mErges seveRal EXcel files tO siNglE file (EacH In sepAratE ShEetS).
the fiLes tHE DATA is
 Invalid input could trigg er. To wor k aro und  th is , yo u co uld try creati n g an  NSNumber from the str ing i np u t an d  i f you  don'tg et a n N SN um ber ,d on 't bo the r react ing untilyou  d o (and if th e  f ield loses  fo cus with inv ali d inpu t,  ch a nge i t b ack t o itsl ast va lid value )b ut the n  you're d up lica ting the "validat e  o n  commit" NSNum berFor ma t te r beh avi or you get  f or fr e e.

 Q: 
I s f ric t ion requiredfor a gravi t y-p ropell ed  ve h icle?
I ha ve a p hysics proj ectthat requ ires m e  to con s truct a  vehic leout  ofh ou se hol dm ate r ia ls( i.e . CDs, d uc ttape,  woo d e n dowe ls,  pop sicle  sticks). Thi s v ehic l e m ust n ot co ntai nany s ort of  prop ul sion generatorsuch  as an en gin eoramotor .  Inste ad,  on ce thevehicle isbu i l t ,it will be release  f r o mthe topof a w o od en wedge th at  wi ll a l l ow th e ve h ic le to be  prope l le dby grav it y. Onc ethe  ve hicle reac hes th e bottom  of t h e wedge, it wi l l continue on t oa le v el t ile  surface an d wi l l on ly r e ly  on the v eloci ty th a t the vehicle gaine dfrom t he we dge for it to  move. The g o al for t hisp ro j ect is to getthe v ehicle tot he farth est d istancepossiblef r om it’ssta rti ngpos i t io n. 
When I am c onst ru cting t his  vehicl e,sho uld  Iai m for a v ery lowco ef fi ci ent  of f r iction b et wee nthe  whee l s of t he ve hicl ean d  th e surfa c et h at i tis  rol lin gon, o r sh o uld  I allo w some fr ict i on?Ikn ow that  friction isre quired for  t hewheels o f the ve hicle to roll, but will frictio n k eep t he v ehicle fr omreachi ngi ts max imum d istan ce ?
A : 

For t he  mo st  part, the a mou nt of  f rict ion bet ween the wheel and gro und doesn't m att er.I f  t hew he e l r ol l s w i t hout slipping,then varyi ng th e coeffici e ntof  fricti on chan ges n o thing s ince stat ic fricti on  doe s not  do work ( Exercise  for ther eader :  w hy do esstatic  f ric tionnot do any  work ?).
Ho we ver, t he fr ic tional f orce between the wheels  and g round  ne eds to be  en o ugh  to overc omethe fricti ona l t orque  be t weenthea xl e a n d the  res t  of the v e hi cle . If  there is t o o muc h fri cti o n agai nstthe axle of the w h eel, the wheel s wo n ' t t urn andyo u'll slide dow n t he i ncline,ki netic frict ion robb in g  youof kin etic e nergy.T h ew ay todeal  wi th this i s t om inimize  f ri c tion a gain st  the a xle an d  mak e the vehicle heav y sot h e whe e lsget a  l ot of t o rque  against t he ground.
 Q:
Clos e tem porarywo rkbook 

I  p icked up t h is code f rom t he web.  I t me rge s seve ralE x cel f iles  t o s ingle fil e (e a ch  i n  se para te sh ee ts). 
The file s  the DAT A i s 
 Invalid_input could_trigger. To work around_this, you_could_try creating_an_NSNumber from the_string input and_if you don't get_an NSNumber, don't_bother_reacting until you do (and if the field loses focus with invalid input, change_it_back to_its_last_valid value) but then you're_duplicating the "validate on commit"_NSNumberFormatter behavior_you get for free.

 Q:

Is friction required for_a_gravity-propelled vehicle?

I have_a physics project that requires me to construct a_vehicle out of household materials (i.e._CDs, duct tape,_wooden_dowels,_popsicle sticks). This vehicle_must not contain any sort of_propulsion generator such as an engine_or a motor. Instead, once the vehicle_is built, it will be release_from the top of a_wooden wedge_that will allow the vehicle_to be propelled_by gravity._Once the vehicle_reaches the bottom of the wedge,_it will continue_onto a level tile surface and_will_only rely on_the_velocity_that the_vehicle gained from_the_wedge for_it_to move. The goal for this_project_is to get the vehicle to the_farthest distance possible from_it’s_starting position. 
When I_am constructing this vehicle, should_I aim for a very low_coefficient of_friction between_the wheels of the vehicle and the surface that it is_rolling on, or should I allow_some friction? I know_that friction_is_required for the_wheels_of the_vehicle to roll, but will friction keep_the vehicle_from reaching its maximum distance?

A:

For the_most part, the amount_of_friction between the wheel and ground_doesn't matter. If the wheel rolls_without slipping, then varying the_coefficient_of_friction changes nothing since static_friction does not do work (Exercise_for the reader:_why does static friction not do any_work?).
However,_the frictional force between the wheels_and_ground needs to be enough to_overcome_the_frictional torque between the axle_and the rest of the vehicle._If there is too much friction against the axle_of the wheel,_the wheels won't turn and_you'll_slide_down the incline, kinetic friction robbing you of kinetic energy._The way_to deal with_this is to minimize friction against the axle and make_the vehicle heavy so the wheels get_a lot of torque against the ground.

 Q:

Close temporary workbook

I picked_up this code from the web. It merges_several Excel files to single file (each_in separate sheets).
The files_the_DATA is