X Fx = F A. If applied force is small, book does not move (static), a x =0, then f=f s

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Abigail McGee
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1 A Appl ewton s nd Lw X 0 X A I pplied orce is sll, boo does not ove sttic, 0, then s A Increse pplied orce, boo still does not ove Increse A ore, now boo oves, 0 > A A

2 here is soe iu sttic rictionl orce, s. Once the pplied orce eceeds it, the boo oves ~ s s ~ Mnitudes not vectors s is the coeicient o sttic riction, it is diensionless nuber, dierent or ech surce-object pir wood-wood, wood-etl; lso depends on surce preprtion s does not depend on the ss or surce re o the object Hs vlue: 0 < s <.5 I no pplied verticl orce

3 Push down on boo A P Appl ewton s nd Lw P 0 P Wht is A needed just to strt boo ovin? 0 A A P P

4 When n Object is Movin? s is eceeded so the object cn ove, but riction orce is still bein pplied. However, less orce is needed to eep n object ovin inst riction thn to et it strted We deine inetic riction is the coeicient o inetic riction, siilr to but lws less thn ow, let s consider incline plne proble, but with riction but irst do sipler eple

5 Eple Proble When ou push.80- boo on tbletop, it tes.5 to strt the boo slidin. Once it is slidin, however, it tes.50 to eep the boo ovin with constnt speed. Wht re the coeicients o sttic nd inetic riction between the boo nd the tble top?

6 Boo is t rest.00, 0.0, s 0.00 BD s s cos cos s 0 cos0.0 o sin sin s 0 sin0.0 o

7 Boo cn ove slide i sin s Wht is s? > Boo does not ove. Wht nle is needed to cuse boo to slide? tn sin sin sin cos tn. o As is incresed, decreses, thereore s decreses

8 Once boo is ovin, we need to use the inetic coeicient o riction Lets te, 5.0 nd 0.50 < s or sin sin sin s s cos sin5.0 cos o 0.50cos5.0 o

9 Eple Proble A sier is pulled up slope t constnt velocit b tow br. he slope is inclined t 5.0 with respect to the horizontl. he orce pplied to the sier b the tow br is prllel to the slope. he sier s ss is 55.0, nd the coeicient o inetic riction between the sis nd the snow is 0.0. ind the nitude o the orce tht the tow br eerts on the sier.

10 Given: 55.0, 0.0, 5.0 Iner: since velocit is constnt, 0; lso 0 since sier reins on slope equilibriu 0 0,! 0 Drw BD, ppl ewton s nd Lw p p

11 cos 0 cos 0 86 sin cos sin cos sin sin 0 sin 0 P P

12 he ension orce BD o crte Crte, rope rictionless Assue rope is ssless nd tut rictionless pulle - BD o rope Crte t rest 0 0

13 Lie the norl orce, the riction nd tension orces re ll niesttions o the electronetic orce he ll re the result o ttrctive nd repulsive orces o tos nd olecules within n object norl nd tension or t the interce o two objects Applictions o ewton s nd Lw Equilibriu n object which hs zero ccelertion, cn be t rest or ovin with constnt velocit 0 0,! 0

14 Eple: boo t rest on n incline with riction on-equilibriu the ccelertion o the objects is non-zero!!, Eple Proble hree objects re connected b strins tht pss over ssless nd rictionless pulles. he objects ove nd the coeicient o inetic riction between the iddle object nd the surce o the tble is 0.00 the other two bein suspended b strins. Wht is the ccelertion o the three objects? b Wht is the tension in ech o the two strins?

15 Given: 0.0, 80.0, 5.0, 0.00 ind:,,,, nd olution: Drw ree-bod dirs Appl ewton s nd Lw to ech object

16 Also, 0, 0, 0 X 0 0

17 hree equtions, but ive unnowns:,,,,nd But, - ubstitute nd nd rd equtions into the st eqution 0

18 s " # $ % & '

20 Eple siple Pullin up on rope, ou lit 4.5- bucet o wter ro well with n ccelertion o.78 /s. Wht is the tension in the rope?

Types of forces. Types of Forces

Types of forces. Types of Forces pes of orces pes of forces. orce of Grvit: his is often referred to s the weiht of n object. It is the ttrctive force of the erth. And is lws directed towrd the center of the erth. It hs nitude equl to