friction theory e
TRANSCRIPT
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^BT]DM]
"h`fdsbiuh`rpbysdms.df" 0
EZDM_DAF0. EZDM_DAF
Wblf twa jaodls `rl ilpt df maft`mt, lclmtrah`gfltdm earmls `mt jltwllf tbl mb rglo p`rtdmcls (haclmucls)
`t tbl sure`mls ae tbl jaodls. _bus, l`mb jaoy lxlrts ` maft`mt earml af tbl atblr. _bl h`gfdtuols ae tblmaft`mt earmls `mtdfg af tbl twa jaodls rl lqu c jut tbldr odrlmtdafs `rl appasdtl `fo tblrlearl tbl maft`mt
earmls ajly Flwtafs tbdro c`w.
_bl odrlmtdaf ae tbl maft`mt earml `mtdfg af ` p`rtdmuc r jaoy ds fat flmlss`rdcy plrplfodmuc r ta tbl maft`mt
sure`ml. Wl m`f rlsacvl tbds maft`mt earml dfta twa mahpaflfts, afl plrplfodmuc`r ta tbl maft`mt sure`ml
`fo tbl atblr p`r cclc ta dt (edgurl. _bl plrplfodmuc r mahpaflft ds m cclo tbl farh c maft mt earml ar farh c
earml ( glflr`ccy wrdttlf `s F) `fo tbl p`r`cclc mahpaflft ds m`cclo erdmtdaf (glflr`ccy wrdttlf `s e).
_blrlearl de Z ds maft`mt earml tblf
Z 8 :: Fe
:. ZL@]AF] EAZ EZDM_DAF
(d) ftlr-camidfg ae lxtlfolo p`rts ae afl ajklmt dfta tbl lxtlfolo p`rts ae tbl atblr ajklmt.
(dd) Jafodfg jltwllf tbl haclmucls ae tbl twa sure`mls ar ajklmts df maft`mt.
=. EZDM_DAF EAZML D] AE _WA _T^L].
`. Idfltdm j. ]t`tdm
(`) Idfltdm Erdmtdaf Earml
Idfltdm erdmtdaf lxdsts jltwllf twa maft`mt sure`mls afcy wblf tblrl dsrlc`tdvl hatdaf jltwllf
tbl twa maft`mt sure`mls. Dt staps `mtdfg wblf rlc`tdvl hatdaf jltwllf twa sure`mls ml`sls.
ODZLM_DAF AE IDFLM_DM EZDM_DAF AF @F AJKLM_
t ds appasdtl ta tbl rlc tdvl vlcamdty ae tbl ajklmt wdtb rlsplmt ta tbl atblr ajklmt df maft mt mafsdolrlo.
Fatl tb t dts odrlmtdaf ds fat appasdtl ta tbl earml `ppcdlo dt ds appasdtl ta tbl rlc`tdvl hatdaf ae tbl
jaoy mafsdolrlo wbdmb ds df maft`mt wdtb tbl atblr sure`ml.
H@GFD_\OL AE IDFL_DM EZDM_DAF
_bl h`gfdtuol ae tbl idfltdm erdmtdaf ds prapartdaf`c ta tbl farh`c earml `mtdfg jltwllf tbl twa jaodls. Wl
m`f wrdtl
ei
8i
F
wblrl F ds tbl farh`c earml. _bl prapartdaf`cdty mafst`ft i
ds m`cclo tbl maleedmdlft ae idfltdm erdmtdaf
`fo dts v`cul olplfos af tbl f`turl ae tbl twa sure`mls df maft`mt.
Lx`hpcl 0. Edfo tbl odrlmtdaf ae idfltdm erdmtdaf earml
(`) af tbl jcami, lxlrtlo jy tbl graufo.
(j) af tbl graufo, lxlrtlo jy tbl jcami.
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"h`fdsbiuh`rpbysdms.df" :
]acutdaf ; ( )
(j)
wblrl e0 `fo e: `rl tbl erdmtdaf earmls af tbl jcami fo graufo rlsplmtdvlcy.
Lx`hpcl :. Df `javl lx`hpcl marrlmt rlc tdaf jltwllf h`gfdtuol ae e0
`fo e:
ds
(@) e06 e
: (J) e
:6 e
0
(M) e0
8 e:
(O) fat passdjcl ta olmdol oul ta dfsueedmdlft o`t`.
]acutdaf ; Jy Flwtafs tbdro c`w tbl `javl erdmtdaf earmls `rl `mtdaf-rl`mtdaf p`dr `fo lqu c jut appasdtl ta
l`mb atblr df odrlmtdaf. Blfml (M).
@csa fatl tb`t tbl odrlmtdaf ae idfltdm erdmtdaf b`s fatbdfg ta oa wdtb `ppcdlo earml E.
Lx`hpcl =. @cc sure`mls s sbawf df tbl edgurl rl raugb. Or`w tbl erdmtdaf earml af @ & J
J
@ 0>h/s
:>h/s
////////////////////////////////////////////////////////
]acutdaf ;
Idfltdm erdmtdaf `mts df sumb ` w`y sa `s ta rlouml rlc`tdvl hatdaf.
Lx`hpcl ?. Edfo aut tbl odst`fml tr`vlcclo jy tbl jcamis sbawf df tbl edgurl jlearl dt staps.
0> ig
0> h/s
///////////////////////////////////////// 8>.g
F
ei
F 0> g 8 >
F 8 0>> F
ex
8 iF
8 s8
iwblf fat hlftdaflo
ex8 >.< 0>> 8 F
Ex8 h`
8 0> ` ` 8 : 8 0>: + : ( h
Lx`hpcl h/s `fo maleedmdlft ae erdmtdaf jltwllf tbl jcami `fo dfmcdfl ds 8 >.
h/s
edxlo
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^BT]DM]
"h`fdsbiuh`rpbysdms.df" =
]acutdaf ; F 8 hg mas=7
hg sdf =7 + F 8 h`
` 8 0> h/s: oawf tbl dfmcdfl
Faw v: 8 u: + :`s
> 8 0>: + :(0>) ]
] 8 < h
Lx`hpcl 5. Edfo tbl tdhl t`ilf df tbl `javl lx`hpcl jy tbl jcami ta rl`mb tbl dfdtd`c pasdtdaf.
]acutdaf ; ` 8 g sdf =7 g mas =7
h/s `fo ` earml ae 0>> F df `oodtdaf ta erdmtdaf earml ds `csa `mtdfg af
tbl jcami. Edfo tbl rlt`ro`tdaf ae tbl jcami1
]acutdaf ; @s tblrl ds rlc`tdvl hatdaf
idfltdm erdmtdaf wdcc `mt ta rlouml tbds rlc`tdvl hatdaf.
ei
8 F 8 >.0 0> 0> 8 0> F
0>> + 0> 8 0>`
` 80>
00>8 00 h/s:
(j) ]_@_DM EZDM_DAF
t lxdsts jltwllf tbl twa sure`mls wblf tblrl ds tlfolfmy ae rlc tdvl hatdaf jut fa rlc`tdvl hatdaf
`cafg tbl twa maft`mt sure`ml.
Ear lx`hpcl mafsdolr ` jlo dfsdol ` raah 9 wblf wl glftcy pusb tbl jlo wdtb ` edfglr, tbl jlo oals
fat havl. _bds hl`fs tb`t tbl jlo b`s ` tlfolfmy ta havl df tbl odrlmtdaf ae `ppcdlo earml jut oals
fat havl `s tblrl lxdsts st`tdm erdmtdaf earml `mtdfg df tbl appasdtl odrlmtdaf ae tbl `ppcdlo earml.
Lx`hpcl 2. Wb`t ds v`cul ae st`tdm erdmtdaf earml af tbl jcami1
]acutdaf ; Df bardzaft`c odrlmtdaf `s `mmlclr`tdaf ds zlra.
_blrlearlE 8 > . 8 >
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"h`fdsbiuh`rpbysdms.df" ?
drlmt daf ae st`t dm e rdmtdaf earml_bl st`tdm erdmtdaf earml af `f ajklmt ds appasdtl ta dts dhplfodfg hatdaf rlc`tdvl ta tbl sure`ml.
Eaccawdfg stlps sbauco jl eaccawlo df oltlrhdfdfg tbl odrlmtdaf ae st`tdm erdmtdaf earml af f ajklmt.
(d) Or`w tbl erll jaoy od`gr`h wdtb rlsplmt ta tbl atblr ajklmt af wbdmb dt ds ilpt.
(dd) Dfmcuol psluoa earml `csa de maft`mt sure`ml ds mmlclr`tdfg.
(ddd) Olmdol tbl rlsuct`ft earml `fo tbl mahpaflft p`r`cclc ta tbl sure`ml ae tbds rlsuct`ft earml.
(dv) _bl odrlmtdaf ae st`tdm erdmtdaf ds appasdtl ta tbl `javl mahpaflft ae rlsuct`ft earml.
Fatl ; Blrl afml `g df tbl st tdm erdmtdaf ds dfvacvlo wblf tblrl ds fa rlc`tdvl hatdaf jltwllf twa
sure`mls.
Lx`hpcl 4. Df tbl eaccawdfg edgurl `f ajklmt ae h`ss H ds ilpt af ` raugb t`jcl `s sllf
erah `javl. Earmls `rl `ppcdlo af dt `s sbawf. Edfo tbl odrlmtdaf ae st`tdm
erdmtdaf de tbl ajklmt oals fat havl.
]acutdaf ; Df tbl `javl prajclh wl edrst or`w tbl erll jaoy od gr`h ae edfo tbl rlsuct`ft earml.
@s tbl ajklmt oal fat havl tbds ds fat ` m`sl ae cdhdtdfg erdmtdaf. _bl odrlmtdaf ae st`tdm erdmtdaf ds appasdtl ta
tbl odrlmtdaf ae tbl rlsuct`ft earml EZ
`s sbawf df edgurl jy es
. Dts h`gfdtuol ds lqu`c ta :< F.
H@GFD_\OL AE IDFL_DM @FO ]_@_DM EZDM_DAFIdfltdm erdmtdaf ;
_bl h`gfdtuol ae tbl idfltdm erdmtdaf ds prapartdaf`c ta tbl farh`c earml `mtdfg jltwllf tbl twa jaodls. Wl
m`f wrdtl
ei
8i
F
wblrl F ds tbl farh`c earml. _bl prapartdaf`cdty mafst`ft i
ds m`cclo tbl maleedmdlft ae idfltdm erdmtdaf
`fo dts v`cul olplfos af tbl f turl ae tbl twa sure`mls df maft`mt. De tbl sure`mls `rl shaatb i
wdcc jl
sh cc, de tbl sure`mls `rl raugb i
wdcc jl c rgl. Dt `csa olplfos af tbl h`tlrd cs ae tbl twa jaodls df maft`mt.
]t`tdm erdmtdaf ;_bl h`gfdtuol ae st`tdm erdmtdaf ds lqu`c `fo appasdtl ta tbl lxtlrf`c earml lxlrtlo, tdcc tbl ajklmt `t wbdmb
earml ds lxlrtlo ds `t rlst. _bds hl`fs dt ds ` v`rd`jcl `fo slce `okustdfg earml. Bawlvlr dt b`s `
h`xdhuh v`cul m`cclo cdhdtdfg erdmtdaf.
eh`x
8 sF
_bl `mtu`c earml ae st tdm erdmtdaf h`y jl sh`cclr tb`f sF `fo dts v cul olplfos af atblr earmls `mtdfg af tbl
jaoy. _bl h`gfdtuol ae erdmtdaf`c earml ds lqu`c ta tb`t rlqudrlo ta illp tbl jaoy `t rlc`tdvl rlst.
> es esh`x
Blrl s
`fo i
`rl prapartdaf`cdty mafst`fts. s
ds m`cclo maleedmdlft ae st tdm erdmtdaf `fo i
ds m`cclo maleedmdlft
ae idfltdm erdmtdaf. _bly `rl odhlfsdafclss qu`ftdtdls dfolplfolft ae sb`pl `fo `rl` ae maft`mt . Dt ds `
praplrty ae tbl twa maft`mt
sure`mls.s6iear ` gdvlf p`dr ae sure`mls. De fat hlftdaflo tblfs8i m`f jl
t`ilf. U`cul aem`f jl erah > ta.
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"h`fdsbiuh`rpbysdms.df" .
]tllc fo jr`ss >.=< _lecaf fo tlecaf >.>?
Gc`ss fo gc`ss 0.>>
Waao fo waao >.=
Waao fo hlt`c >.?> Zujjlr tyrl af wlt
mafmrltl ra`o >.7
Lx`hpcl 0>. Edfo `mmlclr`tdaf ae jcami. Dfdtd`ccy tbl jcami ds `t rlst.
0> Ig
F
8>.> 8 > ear vlrtdm`c odrlmtdaf
F 8 75 F
Faw > es
sF
> es 75 >.es=2 F
=: 3 =2 Blfml e 8 =:
`mmlclr`tdaf ae jcami ds zlra.
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"h`fdsbiuh`rpbysdms.df" 7
Lx`hpcl 0e]
F
hg sdf6 esh`x
hg sdf6 F
hg sdf 6 hg mas
t`f 6 8 t`f0
ear t`f fa scdodfg af dfmcdflo pc`fl.
_bds hltbao ds uslo ear edfodfg aut tbl v`cul ae pr`mtdm ccy.
Lx`hpcl 05. Edfo aut tbl `mmlclr tdaf ae tbl jcami. De tbl jcami ds dfdtd`ccy `t rlst.
]acutdaf ; (EJO ae tbl jcami lxmcuodfg erdmtdaf)
Hgmas
=7
0>ig
7 g mas =7 8 2> F
Faw >esF
>es>.< 2>
es?> F
2>
7
F
Wl wdcc put v cul ae e df tbl c`st d.l. df tbl odrlmtdaf appasdtl ta rlsuct`ft ae atblr earmls. e `mts oawf
tbl dfmcdfl `fo dts v`cul ds ae 8 7< 5> 8 0< F
]a `mmlclr`tdaf ds zlra
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"h`fdsbiuh`rpbysdms.df" 2
Lx`hpcl 07. Df tbl `javl prajclh baw humb earml sbauco jl `oolo ta 7< F earml sa tb t jcami st rts ta havl
up tbl dfmcdfl.
]acutdaf ; 5> + ?> 8 7< + elxtr`
es8 :< F
Lx`hpcl 02. Df tbl `javl prajclh wb t ds tbl hdfdhuh earml jy wbdmb 7< F earml sbauco jl rlpc mlo wdtb sa tb`t
tbl jcami oals fat havl.
]acutdaf ; Df tbds m`sl tbl jcami b`s ` tlfolfmy ta havl oawfw`ros.
Blfml erdmtdaf `mts upw`ros.
E
?>
5>
E + ?> 8 5>
E 8 :> F
Lx`hpcl 04. _ap vdlw ae ` jcami af ` t`jcl ds sbawf (g 8 0> h/s:) .
Edfo aut tbl `mmlclr`tdaf ae tbl jcami.
]acutdaf ;
?> g
?>F
E 8 ?>Z
:?> 8 . Edfo hdfdhuh sa tb`t tbl jcamis rlh`df st`tdaf`ry.
]acutdaf ; _ 8 0>> g 8 0>>> F 0>>>
ee 8 0>>> ta illp tbl jcami st`tdaf`ry
Faw eh`x
8 0>>>
F8 0>>>
8 :
M`f jl grl`tlr tb`f 0 1
Tls > 3
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"h`fdsbiuh`rpbysdms.df" 4
Lx`hpcl :0. Edfo aut hdfdhuh `mmlclr tdaf ae jcami @ sa tb t tbl 0> ig jcami oalsft e`cc.
]acutdaf ;
0> g
0>F`
F@ppcydfg FC df bardzaft`c odrlmtdaf
F 8 0> ` ......... (0)
@ppcydfg FC df vlrtdm`c odrlmtdaf
0> g 8 F .......(:)
0> g 8 0> ` erah (0) & (:)
` 8
g8 :> h/s:
Lx`hpcl ::. Edfo tbl tlfsdaf df tbl strdfg df sdtu tdaf `s sbawf df tbl edgurl jlcaw. Earmls 0:> F `fo 0>> F st rt
`mtdfg wblf tbl systlh ds `t rlst `fo tbl h`xdhuh v cul ae st tdm erdmtdaf af 0> ig ds 4> F `fo tb`t af
:> ig ds 5>F1
]acutdaf ; (d) Clt us `ssuhl tb t systlh havls taw`ros clet tblf `s dt ds mcl`r erah EJO, flt earml df bardzaft`c
odrlmtdaf ds taw`ros rdgbt. _blrlearl tbl `ssuhptdaf ds fat v`cdo.
@javl `ssuhptdaf ds fat passdjcl `s flt earml af systlh mahls taw`ros rdgbt. Blfml systlh ds
fat havdfg taw`ros clet.(dd) ]dhdc`rcy clt us `ssuhl tb`t systlh havls taw`ros rdgbt.
@javl `ssuhptdaf ds `csa fat passdjcl `s flt earml af tbl systlh ds taw`ros clet df tbds sdtu`tdaf.
Blfml `ssuhptdaf ds `g`df fat v`cdo.
_blrlearl dt m`f jl mafmcuolo tb`t tbl systlh ds st`tdaf`ry.
@ssuhdfg tb`t tbl 0> ig jcami rl`mbls cdhdtdfg erdmtdaf edrst tblf usdfg EJOs.
0:> 8 _ + 4> _ 8 => F
@csa _ + e 8 0>>
=> + e 8 0>>
e 8 7> F wbdmb ds fat passdjcl `s tbl cdhdtdfg v`cul ds 5> F ear tbds sure`ml ae jcami.
Aur `ssuhptdaf ds wrafg `fo faw t`idfg tbl :> ig sure`ml ta jl cdhdtdfg wl b`vl
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"h`fdsbiuh`rpbysdms.df" 0>
_ + 5> 8 0>> F _ 8 ?> F
@csa e + _ 8 0:> F e 8 2> F
_bds ds `mmlpt`jcl `s st`tdm erdmtdaf `t tbds sure`ml sbauco jl clss tb`f 4> F.
Blfml tbl tlfsdaf df tbl strdfg ds
_ 8 ?> F.
Lx`hpcl :=. Df tbl eaccawdfg edgurl earml E ds gr`ou ccy dfmrl`slo erah zlra. Or`w
tbl gr`pb jltwllf `ppcdlo earml E `fo tlfsdaf _ df tbl strdfg. _bl
maleedmdlft ae st`tdm erdmtdaf jltwllf tbl jcami `fo tbl graufo ds s
.
]acutdaf ; @s tbl lxtlrf`c earml E ds gr`ou`ccy dfmrl`slo erah zlra dt ds
mahplfs`tlo jy tbl erdmtdaf `fo tbl strdfg jl`rs fa tlfsdaf. Wblf
cdhdtdfg erdmtdaf ds `mbdlvlo jy dfmrl sdfg earml E ta ` v cul tdcc shg,
tbl eurtblr dfmrl`sl df E ds tr`fselrrlo ta tbl strdfg.
Lx`hpcl :?. Earml E ds gr`ou`ccy dfmrl`slo erah zlra. Oltlrhdfl wbltblr tbl jcami wdcc edrst scdol ar cdet up1
]acutdaf ; _blrl `rl hdfdhuh h`gfdtuol ae earmls rlqudrlo jatb df bardzaft`c `fo vlrtdm`c odrlmtdaf ldtblr ta
scdol af cdet up tbl jcami. _bl jcami wdcc edrst scdol af cdet up wdcc olplfo upaf wbdmb hdfdhuh h`gfd-
tuol ae earml ds clsslr.
Ear vlrtdm`c odrlmtdaf ta st`rt cdetdfg up
E sdf =7 + F Hg >.
F jlmahls zlra kust cdetdfg mafodtdaf.
Ecdet
Ecdet
=
>F
Ear bardzaft`c odrlmtdaf ta st`rt scdodfg
E mas =7 sF
E mas =7 6 >.< Y 0>g E sdf =7X ( F 8 0> g E sdf =7)
Blfml Escdol
6=7sdf=7mas
Escdol
600
>F
Ecdet
6=
>F.
Escdol
3 Ecdet
_blrlearl tbl jcami wdcc jlgdf ta scdol jlearl cdetdfg.
_WA JCAMI ^ZAJCLH]
LR@H^CL : J
]haatb
8>.< 0> @ E 8 F
//////////////////////////////////////////////////
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"h`fdsbiuh`rpbysdms.df" 00
]acutdaf ; Hltbao ae sacvdfg
]tlp 0 ; H`il earml od`gr`h.
]tlp : ; ]baw st`tdm erdmtdaf earml jy e jlm`usl v`cul ae erdmtdaf ds fat ifawf.
]tlp = ; M`cmuc`tl slp`r`tlcy ear twa m`sls.
M`sl 0 ; Havl tagltblr
]tlp ? ; M`cmuc`tl `mmlclr`tdaf.
]tlp < ; Mblmi v`cul ae erdmtdaf ear `javl m`sl.]tlp 5 ; De rlqudrlo erdmtdaf ds clss tb`f `v`dc`jcl dt
hl`fs tbly wdcc havl tagltblr lcsl
havl slp`r`tlcy.
]tlp 7; (`) `javl `mmlclr tdaf wdcc jl mahhaf
`mmlclr`tdaf ear jatb
M`sl : ; Havl slp`r`tlcy
]tlp 7(j) De tbly havl slp`r tlcy tblf idfltdm erdmtdaf ds dfvacvlo. wbasl v`cul ds F.
]tlp 2 ; M cmuc tl `mmlclr`tdaf ear `javl m`sl.
e
@ eJ
eh`x
8 F
e F (`v`dc`jcl erdmtdaf)
Havl tagltblr Havl slp`r`tlcy
(d) ` 80>0>
8 :.< h/s: Fa fllo ta m`cmuc`tl
(dd) Mblmi erdmtdaf ear J ;
e 8 0> :.< 8 : J
8>. @ 0>0 F
//////////////////////////////////////////////////
]acutdaf ; eh`x 8 < > Fe F
0>0
e
@
e
J
(d) De tbly h avl tagltblr ` 8:>
0>08 < h/s:
(dd) Mblmi erdmtdaf af J
e
0> e 8 0> < 8 .< (rlqudrlo)
.< 6 (tblrlearl rlqudrlo 6 `v`dc jcl)
Blfmltbly wdcc fat havl tagltblr.
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^BT]DM]
"h`fdsbiuh`rpbysdms.df" 0:
(ddd) Blfml tbly havl slp`r`tlcy sa idfltdm erdmtdaf ds dfvacvlo.
0>0
e 8i
@
e 8 F8i
J
ear @
80>
0>08
8 < h/s:
@csa @
6 `J
`s earml ds `ppcdlo af @.
Lx`hpcl :7. Edfo tbl `mmlclr`tdaf ae tbl twa jcamis. _bl systlh ds dfdtd`ccy `t
rlst `fo tbl erdmtdaf maleedmdlft `rl `s sbawf df tbl edgurl1 :>]haatb
8>.
E 8 5> F
///////////////////////////////////////////
]acutdaf ; Havl _agltblr Havl ]lp`r`tlcy
` 8=>
5>8 : h/s: Fa fllo ta m`cmuc`tl.
Mblmi erdmtdaf af :> ig.
e 8 :> x :
e 8 ?> (wbdmb ds rlqudrlo)
?> 3 (tblrlearl rlqudrlo 3 `v`dc`jcl)
wdcc havl tagltblr.
Lx`hpcl :2. Df `javl lx`hpcl edfo h`xdhuh E ear wbdmb twa jcamis wdcc havl tagltblr.
]acutdaf ; Ajslrvdfg tbl mrdtdm c sdtu`tdaf wblrl erdmtdaf jlmahls cdhdtdfg.
E
e 8 h`x0>
e 8 h`x:>
E eh`x
8 0> ` ......... (0)
eh`x 8 :> ` .......... (:)
E 8 7< F
Lx`hpcl :4. Dfdtd`ccy tbl systlh ds `t rlst. edfo aut hdfdhuh v`cul ae E ear wbdmb
scdodfg st`rts jltwllf tbl twa jcamis.:>
]haatb
8>.
E
////////////////////////////////////]acutdaf ; @t kust scdodfg mafodtdaf cdhdtdfg erdmtdaf ds `mtdfg.
e 8 0> E
e 8
:>
E 8 :> ` ........... (0)
e 8 0> ` .................. (:)
8 0> `
` 8 < h/s:
blfml E 8 + :> < 8 0 F
Ehdf
8 0 F
Lx`hpcl =>. Df tbl edgurl gdvlf jlcaw earml E `ppcdlo bardzaft`ccy af cawlr
jcami, ds gr`ou`ccy dfmrl`slo erah zlra. Odsmuss tbl odrlmtdaf
`fo f`turl ae erdmtdaf earml `fo tbl `mmlclr`tdafs ae tbl jcami
ear odeelrlft v culs ae E (_ il g 8 0> h/s:).
]acutdaf ; Df tbl `javl sdtu`tdaf wl sll tb`t tbl h`xdhuh passdjcl v`cul ae erdmtdaf jltwllf tbl jcamis ds
sh
@g 8 >.= 0> 0> 8 => F.
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^BT]DM]
"h`fdsbiuh`rpbysdms.df" 0=
M`sl (d) Wblf E 8 A.
Mafsdolrdfg tb`t tblrl ds fa scdppdfg jltwllf tbl jcamis tbl `mmlclr`tdaf ae systlh wdcc jl
` 80>:>
0:>
8 ? h/s:
Jut tbl h`xdhuh `mmlclr`tdaf ae J m`f jl ajt`dflo jy
tbl eaccawdfg earml od`gr`h.
`J
8:>
=>8 0.< h/s: ( afcy erdmtdaf earml jy jcami @ ds rlspafsdjcl ear praoumdfg `mmlclr`tdaf df
jcami J)
Jlm`usl ? 6 0.< h/s: wl m`f mafmcuol tb`t tbl jcamis oa fat havl tagltblr.
Faw or`wdfg tbl E.J.O. ae l`mb jcami, ear edfodfg aut dfodvdou`c `mmlclr`tdafs.
@8
0>
=>0:>8 4 h/s: taw`ros rdgbt
`J
8:>
=>8 0.< h/s: taw`ros rdgbt.
M`sl (dd)E ds dfmrl`slo erah zlra tdcc tbl twa jcamis kust st`rt havdfg tagltblr.
@s tbl twa jcamis havl tagltblr tbl erdmtdaf ds st`tdm df f`turl `fo dts v`cul ds cdhdtdfg. EJO df tbds m`sl
wdcc jl
`@
80>
=>0:>8 4 h/s: `
J
8:>
=>E 8`
@
:>
=>E 8 4
E 8 0 F
Blfml wblf > 3 E 3 0 F tbl jcamis oa fat havl tagltblr `fo tbl erdmtdaf ds idfltdm. @s E
dfmrl`sls `mmlclr`tdaf ae jcami J dfmrl`sls erah 0.< h/s:.
@t E 8 0 F cdhdtdfg st`tdm erdmtdaf st`rt `mtdfg `fo tbl twa jcamis st`rt havdfg tagltblr.
M`sl (ddd)Wblf E ds dfmrl`slo `javl 0 F.
Df tbds smlf rda tbl st`tdm erdmtdaf `okusts dtslce sa `s ta illp tbl jcamis havdfg tagltblr. _bl v`cul
ae st`tdm erdmtdaf st`rts rloumdfg jut tbl odrlmtdaf stdcc rlh`dfs s`hl. _bds b`pplfs maftdfuauscy tdcc
tbl v`cul ae erdmtdaf jlmahls zlra. Df tbds m`sl tbl EJO ds `s eaccaws
@8 `
J8
0>
e0:>8
:>
eE
wblf erdmtdaf earml e glts rloumlo ta zlra tbl `javl `mmlclr`tdafs jlmahl
@8
0>
0:>8 0: h/s: `
J8
:>
E8
@8 0: h/s:
E 8 :?> F
Blfml wblf 0 E :?> F tbl st tdm erdmtdaf earml maftdfuauscy olmrl`sls erah h`xdhuh ta zlra
`t E 8 :?> F. _bl `mmlclr`tdafs ae tbl jcamis dfmrl`sl erah 4 h/s: ta 0: h/s: ourdfg tbl mb`fgl ae
earml E.
M`sl (dv) Wblf E ds dfmrl`slo `g`df erah :?> F tbl odrlmtdaf ae erdmtdaf earml af tbl jcami rlvlrsls jut dt ds
stdcc st`tdm. E m`f jl dfmrl`slo tdcc tbds rlvlrslo st`tdm erdmtdaf rl`mbls dts cdhdtdfg v`cul. EJO `t tbds
kufmturl wdcc jl
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8/12/2019 Friction Theory E
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^BT]DM]
"h`fdsbiuh`rpbysdms.df" 0?
_bl jcamis havl tagltblr tblrlearl.
@8
0>
=>0:> 8 0< h/s: `
J8
:>
=>E 8
@8 0< h/s:
:>
=>E 8 0< h/s:
Blfml E 8 ==> F.
M`sl (v) Wblf E ds dfmrl`slo jlyafo ==> F. Df tbds m`sl tbl cdhdtdfg erdmtdaf ds mbdlvlo `fo scdppdfg t`ils
pc`ml jltwllf tbl jcamis (idfltdm erdmtdaf ds dfvacvlo).
@
8 0< h/s: wbdmb ds mafst`ft
`J8 :>
=>E
h/s: wblrl E 6 ==> F.