高中物理重难点解析：功与能

《高中物理重难点解析：功与能》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。

ஹᡂ1ஹḄᭆᑮ!᪗#ᨵ%&'()᪗*ᳮ,#-ᙠḄ/᎛#(*123ᵨ56W=Rcosa,789ᝅ;<56=>?ᜧᔡ#BC<56DEE〉ᵨGឤIJ஺2ஹ*ᮣMNᵨO*PᳮO*Pᳮ)ᱥᳮ3ᵨRSTUḄVPᳮ#3ᵨO*PᳮᨵWXY#')Z

11ஹ«[ᭆḄᳮ,ஹḄSᵨ)I¬Ḅ®#ᐸ¯ᵨᦔ±)ᦋjᱥ³ḄO*#IJᨵ£V´µḄ¶Iᱥ³ᙠIḄᔣ;Ḅ¬#¸£V¶Z/¹ᙠ#Iºᱥ³J஺»ᐸ⌕¼2#½ᨵ%&#')᪗#Ḅ%&⊤iᔣ#EE)⊤iIJ%¾)¿ÀIJ஺ḄSᵨᨵ8(1)Ḅ56W=Flcosa,ᐸ/cosa)IḄ¯ᵨÁIḄᔣ;Ḅ¬#<56Â⌕ᵨGdឤIJÃ/JÅឋjᓄḄjI(È/ÉÊËÌᙳÎ)(2)56w=p/,〉ᵨGdឤIJ#Ð〉ᵨGd8ឤP᳛JḄjI஺(3)ᵫO*PᳮW=A£KdឤIJ#Ð8djIJ஺(4)᪷ÔF-sÕÖḄᱥᳮ×ØIᱥ³JḄ#᝞Õ5-1ᡠÕ5-1i#Õ▢ÜÝᑖ☢ḄᦪÎàGḄᜧá#'⌕â×#ãä;Ḅ☢⊤iJ%#ãäḄ☢⊤iJ&஺(5))*ᓄḄ¨#ᵫÈ#GᜧáஹᔣåÃ/jᓄḄjIÉᡠJḄ#8æxᱥᳮxyḄᑖ᪆#ç*ᓄXµḄè

2¨ᩭd,஺ë1᝞Õ5-2ᡠi#ð9mḄáᱥ³☟óᙠᬪᱥ᜛/³Ḅöè96Ḅᐝùú☢;#ᬪᱥ³ᙠûÌüIF¯ᵨ---5-2ᔣþ¬OÿS,ᙠᬪᱥᱥḄ.A.0B.mgscos0C.FsD.mgstan0ூ
⚪௃ᙠ&'(⚪*+,⌕./ᑮ123+4ᱥ5ᬪᱥ6☟894:;☢ᐝ>஺ூ᪆௃@A:;☢ᐝ>ᡠCᱥDEFGHI☢ḄJᢝGLᱥMᬪᱥ+NᔣPQRᦑ9GᔠGUᔣVWᔣPᓽFGHJᢝGḄYZᑖGW⊝ᱥᡠEḄᔠ᜜G^4ᬪᱥᱥJᢝGḄVWᑖG(GᜧAmgtanB,LᱥᔣPQR`as,ᡠCAmgstan8,cᫀe⌱D஺ூ௃ᑭᵨᬪᱥᱥḄJᢝGḄYZUᔣḄᑖG5FGW⊝ᩩjklmJᢝGḄᜧnolmJᢝGḄVWᑖGᜧ஺p2:+stuᙠWZvwxnyz■஺|}~y*`as,*ាᑮᐸᨬᜧyzR}C,᳛tuᡠEGឤAᨴᑣᙠ*RᡠḄA.A.FsB.PtC.-mv+Fs--mv^D.F-ᓃ+-tmK222ூ
⚪௃&⚪⌕./ᑮR}C,᳛

3᪵ᱫ¢Gᜧ4£ᓄḄlᱫ¢GḄ^¥¦ᵨv§W=F/cosa,o⌕¨©ª«஺ூ᪆௃@AR,᳛AP,*At,ᦑRᡠḄk⊤APt,B®¯°±⌕./ᑮlRḄ±kCᵨR¦,ᳮ,ᓽW-Fs=-inv--mv^ᡠCW=Lmv+Fs--mv^,C®¯ᡠmmx2222C³⚪cᫀe⌱BC஺ூ௃³⚪᧕┯¶ᜐ^ᙠ¸᧕¹ᱫ¢Gᑖ᪆ᡂឤGoeᵨW=Fsl¼஺p3:ᵨ½┴¿+½┑Áᐭᩈᙽᩈᙽ½┑ḄG5½┑ᐭᩈᙽᑁḄÆzᡂ®Ç.ᙠ½┴ÁÈ+É*¦¹½┑Áᐭᩈᙽᑁ1cm.ÊÁÈ9É*¦ÁᐭËÌÆzÍ(½┴ÏÉ6)ூ
⚪௃k᪷ÒG5Æzᡂ®Ç+ᱯ2¿£GlÔᓄAlWᙳGḄᦔ×ØÙkÚÇÛQÜᵨÚÝ᪷Òᒴ£yZßyz-*áâlãQḄU§᪷Ò6xáâl.ூ᪆௃¼«+3(WᙳG«)½┴ÏÉäᵨᩭæç½┑GḄè᥅êG¥4ឤGᐸᜧ5Æzᡂ®ÇᡝᔠᡃkᵨWᙳGᩭØ×.᝞á5-3ᡠÈ+ÉÁᐭÆzAîWᙳG=1PïANPÈ9ÉÁᐭÆzAðᑮîWᙳGk=gò+M),ãQAA-/Ap=ᨴ(Xi-X)=-^(Xi-Xx).x

41É63%=%.¼ᨵ:^=V2xi=l.41cm,öᔊ+¥=0.41cm.¼«93áâ«@AGøP£,CøAúᙶ᪗᜛UᔣxḄãQ£Aþᙶ᪗møᱏ
᝞5-4ᡠ☢Ḅ┑Ḅ஺ᵫᦑᨵ*£☢,ᓽ:-kx^=-k%+Tiᔊ(M,22ᡠ)*E-,=0.41cmூ./௃ᑭᵨ3ᙳ565Ḅᡈὅᑭᵨ9ᱏ
6☢;ᑮ5Ḅ=>?@Aᵨ,BCᙠEFG⚪IAᵨJᜧL᝞EFMNM5ḄᱯPQR)ᵨ=>?@஺2ஹTUᳮWXYZᳮᐙᑖᑭᵨᐸ^_ឋXYZᳮ,abᱥdeXfghḄi⁚klᵨmᜐᳮopG⚪(q⌕LAᵨstuvZwxeXyz{|}?~ImR)Why▤ᵨsteXZw@6WḄ(p5G⚪xeXG⚪klYᵨXYZᳮWḄG⚪ᐸ,abxIḄG⚪AᵨXYZᳮW஺AᵨXYZᳮWG⚪I⌕)P1
.ᱥdḄ5ᑖ᪆(Z⌕ᑮ,5,B5஺

5(2).ᑖ᪆5Ḅ5,.B஺(3).ᨵḄ5,¡ᙠᱥdeXḄᐰfg£¤ᱥdḄeX¥᝱x5§¨©ªᓄᱥdḄeX¬ᑖᡂª,Ḅfgklᙠὃ⇋᜜5I±²³´5ᙠµfg,,Y(ᭆ·}ᐰfg஺(4).¸ᱥdḄeXᵫᱥᳮfg¹ᡂIº,◤⌕ẆFᐰfgḄh¥᝱IR)½=ᱥᳮfg³ᡂ(᦮dfg¿ÀÁÂᑖ᪆eXfgḄᐹdi⁚=IeᵨXYZᳮᐹᨵfgÄÅஹ?@ÆᝯஹÈÉÄᓫ^P஺Ë4:(ᑡÍÎᵫÏÎᱫÑÒÓ3Ô⍝Ö×fIt,ᐸᵫ0ØᜧᑮV஺ÙÚᑡÎ.Û}M,ÏÎ᳛PÝᢝ,ᑡÎᡠß5f}ឤ5஺6=IᑁᑡÎâfḄãg஺ூä⚪௃)ᑡÎ}ẆF
Ó3?ᔣᱫÑ5Fxß5f,C⌕ÏÎ᳛Ýᢝ,QæÅᱫÑ5ᜧçᓄḄÀᙠhy▤ᵨḄZè{6⌕6Fឤ5஺ூW᪆௃)ᑡÎ}ẆF
ᑡÎÓ3?ᔣᱫÑ5xß5éᑡÎâfãg}s஺᪷ëXYZᳮW-W=|A/V2FfW=P•tFP•t-fs=&Mv22

6Pt-^Mv2W;s=-----------oூ௃¨XÏḄìí᳛PឤZIëP=FVRÚvᓄFQᓄᱫÑ5Fᓄaᓄ஺AïᱥᳮðIᓄḄñwᨵZឋḄ·ò☢âf
óíZឋñw஺᝞5-5ᡠ5-5Ë5oᙢõöḄö20m/s,÷øḄù°=1.3kg/nr(ö5¨ᵯÏḄᨵᦔö☢}^=20m2,᝞üöâfö5¨ᵯÏýöþ}12m/s,ÿ
ᵯḄᦔ᳛஻=80%,ᑣ
ᵯḄᵯ᳛ᜧூ
⚪௃

ᵯ
Ḅᓄᵯ⌕!"ᑮ$Ḅ%&ᨵᐰ)ᓄᵯ*ᨵ+,ᦔ᳛-⚪஺ூ᪆௃
ᵯ01
Ḅᓄᵯ2345ᑁḄ78ᓄ7945ᑁ
ᵯḄ:;0+,

7Pt=_Oᑗ=QRᔩ"7+U2VᐭᦪYZ[V53kWூ`௃Zbc-⚪⌕!"ẆefgḄ⌱ij<⌱kt45m☢Ḅ᥅pqᦪrstᢱvS஺Ḅxy

8ÎÏᐵ᥅pµÑᡂÍÓ஺3ஹÔᡷÖឤᩩÙᢕÛÜÝ᝱ßàÖឤáâãឋᙠᱥᳮᓄḄæçᙠḼéêḄᐵëᡈḄGᙠ23+,ᱥᳮᓄ4fᐸḄᔜ,GᡈGḄᓄᐵëÇᑖ᪆îïᑮ᦮,ᡈñçᙠḼḄᐵëᡈḄGᑣᡂẆe7+ᓄḄḄò´ᐵó஺7§0ᱥᳮ¢ᨬæᵨᑮḄ+8ôõöá++Öឤá஺A▤9øùᑮḄÖឤGú⌕ᨵûü"ýḄ“G”ᩩ▲ᑴḄ“”⌕▊ឤḄᵨ஺✌ᐜᔲឤḄᑨᔲᵨឤḄ!"஺ឤḄᩩ#$ᨵ&'ᡈ)'*+஺,-./01234567᪵ᳮ:⌕ᑖ᪆=ᱥ?ᔲឤ6ᐜ@Aᱥ?BCD'ᑖ᪆EAᱥ?$D&'ᡈ)'FᵨᑣAᱥ?ឤEDᑮᐸJḄ'ᑣKᐸJ'ᔲ*+EᐸJ'L*+ᑣMឤEᐸJ'M*+NKO'*+ḄPᦪᔲRSE*+ḄPᦪRSᑣT᪵ឤ஺ᨵU@V2ᩭX,'*+ḄZ[L\ᑨ]6^_`ᓄbcᩭᑨEV2ᑁ$ᨵefḄgh`ᓄijkᐸJlmḄ`ᓄᑣV2Ḅឤ஺ᑨnoឤpq67᪷sឤḄ⊤umᑡwx:yz⚪|ឤḄ⊤um⌕ᨵ7}~#(1)E+E=E+EᓽឤḄx=᝱K]P}K2P2

9Ḅ_g஺(2)A£.=-\EᓽឤUV2(ᡈ)ḄepV2(ᡈ)Ḅf஺(3)\E=-\EᓽᵫᑖAஹBᡂḄV2ឤUAAKᑖ(ᡈ)ḄBᑖ(ᡈ)Ḅ஺75ᔜmᙳR᪗_mp=⊤umẆḄ¡ᓄ_j◤⌱¤Sf☢ᨵOz⚪ᑭᵨ§¨:y©ª«¬w®⌕ᑖn¯~_¯~_ᡈ¯=ᱥ?¯=ᱥ?஺i@_ឤ6^7=bcᳮ:#(1)±~lmḄ_²ᙠᐸJlmḄ_´__g஺(2)±=ᱥ?Ḅ_²ᙠᐸJᱥ?Ḅ_´__g஺N¶7#᝞¹5-7ᡠ½᪷¾R/ḄÀÁÂÃᙠ஺Äo¹5-7ÆÂÇ=È_RÉḄÊᳫ.ᵨ᜜'ÍÊᳫ"ᑮ¹½ÎÏÐÁÑÒÓᙠ஺ÄḄÔÕ☢5wkÔÕ☢ᡂ30°b.^☟ÙÚÛÊᳫÜÊᳫÝ0ÄÞwUÁḄß'ᜧÊ஺ூâ⚪௃@.⚪⌕BCääåᐭḄᑖ᪆wmL⌕çè|éÁ^ÑÒᑮ@Êᳫᨵß'RÙḄêᨚxḄìᜫLÒî@Êᳫ^ïÎÏᑮðÎÏᑡឤḄwxÜñஹjᨬôÄõc஺]]ᵯூ:᪆௃⌱ÊᳫRẆ@øᐸùex6ᑖRú=▤஺¹5-8

10ý᝞¹5-8ᡠ½:(1)^/ᑮ᜛Ḅ
ᵫ.ឤmgl=-mVi2(2)ᙠ8ᨵᨚḄᳫḄ!ᳫḄ"#ᵫ$%ᔣ'Ḅ“)*ᑗᔣḄ,!!-.ᑣᨵK/=/COS30஺(3)ᳫᵫᐘ0ᑮ஺0Ḅ34!ឤᑣᨵ:-mv/2+mgl(1-cos60°)=-mvcs222ᙠ஺0ᵫ789:T-mg=m^-ὶ<=>?@AT-lmg2ூ௃ᙠᑖ᪆D⚪FG⌕IJᙠKLMN!ᨵOᜫ!QRST᦮VWXឤ!XᵫᐰឤAZD[⚪!\SᙠDMN]^_]`ḄaVbSឤḄ!@ᑖcᵫឤdA஺e8:᝞g5-9ᡠi!ᨵG᪷kᩚAB,@m00ᙠ$%n☢/fᑁ
ᵫr!ᙠABsᔜuGvw*mḄᳫ!0A_0BḄ6-------Bx#ᑖc*2a_a,yzF!AB☟|ᙠ}n!~`!ABᩚrᑮ$%!AஹBasᳫḄ"#ᔜS1g5-9ூ
⚪௃*aᳫuᙠkᩚḄas!ᩚGrF!ᐹᨵḄ"#!ᑣr!aᳫḄ4"#ᡂ஺F⌕IJᑮaᳫᙠr!ᩚb!ᓽVᳫᩭT!WXឤ஺ூ᪆௃aᳫᡂḄ᜜ᨵwrᓄ!DS

11ឤḄ!ᦑD¡}nᑮ$%Ḅ@ᵫឤ:2cmga-mga=~I^mv21mv2AB¦v=2vAsᓃ=2ᡠ=@Aூ௃D⚪Ḅᐵ¬]ᜐᙠ®!Vᳫᩭ¯WXឤ,\aᳫᡂḄᩭ¯SឤḄ஺e9:᝞g5-10ᡠi!±²Ḅ"#*3m/s,aᙊ´µ-----¶·s=4.5m,¸¹ni=lkgḄᱥkᙠ»¼>?Ḅ±²g5-10>!ᱥ±²NḄ᥅¾ᦪ*N=0.15,ᵯ²±²¹ᱥ¡»¼>?〈ᑮ¼>?F!ᵯÃὑḄᵯSூ
⚪௃ᙠÅ⚪⌕ᑖ᪆ÆÇᱥÈF"#ÉᑮÊ〈²!:ὅ"#]`!ᱥRᒴ"%4஺ᓽᱥᙠ¡»>?Â>?Ḅ@G%ᒴÍ"%4!Q@ᐜᒴÍ"%4!`ᒴ"%4஺ூ᪆௃ᱥᙠÏ!ᙠ᥅¾ÐÑᵨ'ᒴÍ"%4,a!=஻g=1.5m/s2ᑣm_v_3§_2stÏFN'aL5!s1,125=—at=—xl.5x2-m=3mᱥᙢ☢Ḅà22

12,W,=—mv2=—x1x9J=4.5J᥅¾ÐᱥḄ22ᱥ±²NḄà‘EL"஺'2-1Í=3ÍçèéᑖḄwê=ig!=0/5x1x10x3/=4.5/¡î!ᵫwឤ@ᵯÃὑḄᵯ*`=%+%=91/ூòó௃ᙠD⚪!᪷wឤ@õ!ᵯÃὑḄᵯᨬ÷rᓄ*ᱥḄ_øùḄè!ú⌕dûᱥüÍḄ_üÍḄèRXýdûᵯÃὑḄᵯ஺4ஹᳮAᐵ!ᱞ“ᓄḄ”ᱥḄ⚞ᓄḄᱥ᝱஺ḄᓄḄ!Ḅᙠ#$ᱥᓄ%!Ḅᙠᱥ&ᓄ஺'()*ᓄḄᐵ,⌕ᨵ!/01(1).6'7ᱥᱥḄ6'8#9:ᓄ6'8Ḅ:ᓄ;<6'ḄᨵᐵW=-^E,=᜜?@?'7ᱥCPA?@?ឋ8Ḅ:ᓄ%ᨵCDᐵW=-^E.FP(2).ᔠ᜜'7ᱥḄHᱥIḄ:ᓄJ%=M/—#I9ᳮ஺(3).◀ᑁḄ6'*?@?'᜜ᐸU'ḄVHWXḄ:ᓄYᐳU'="--]ᳮ஺

13^10:#aᙳᒴdeḄfg6hG,AஹBlmn9ᙠᜩpqr᝞t5-11ᡠwxᙠᨬz{C}~#ᔣ/cḄ'fD{ᙠ)fgABḄ6()t5-11A.⌲ᓣB.⌲zC.ᐜzᓣD.:ூ⚪௃ᙠC{}~ᔣ/Ḅ'fD{ᑣ᜜'7f஺ூ᪆௃ᙠC{}~ᔣ/Ḅ'ᨵᓄhfḄWXfḄI¡~ᡠ!fḄ6'8¡~ᓽfḄ6ᓣᡠ!⚪£¤ᫀhA஺ூV¦௃ᓄḄ7ffḄ#9¡~⊤¨h6'8¡~஺^11᝞t5-L2ᡠwahmḄ«¬ᙽA!®¯°v஺²rahMஹeh/ஹᐝ¶®¯☢CrḄᩈqB,¹ºᩈqrᣵ/¼½AஹB&ḄI᥅¿ÀᦪhÂÃᩈq7ᙢÅhs,ÇÈ#)(1)ᩈq¡~ḄI??A(2)«¬ᙽÊḄIT7(3)WXḄÊt5Â2(4)ÌÍḄÎ஺

14ூ⚪௃ᙠ)᥅¿'ḄÏÐA*BᡠÑ᥅¿'ᑖÓhFlஹF,KF=F=Mmg,AᙠFiḄÔᵨ/ᒴÊ°BᙠF2ḄÔᵨ/212ᒴ~°ÖA¶IᑮBḄØmÃAஹBÙᑮ#᪵Ḅ°v,¹ᣵ/஺ூ᪆௃(1)7B᪷ÜI9ᳮÝYᘊ=ß2#0ºr½\E=/LimgsKB(2)¶I᥅¿'7«¬ᙽAà᪷Üᐵ½'()=#஻"7gG+0ᓽ«¬ᙽÊḄIh—4=Jmv2#;஻zu2=஻mgG+1)0(3)WXḄÊ=1mv2-^ntv2-^Mv2=/.nngl0(4)mஹMã7ÅhI,᪷ÜäឤÝQ=/jmglூV¦௃æ⚪!çè᥅¿'º!/l$é☢ᳮ(1)ãêÔᵨḄ#7☟᥅¿'᝞ì#$'=#$'#9àíîïãHᓽ#7☟᥅¿'ðÌÍÎ஺(2)ãêÔᵨḄ#7¶I᥅¿'Ḅñᦪ*#9hàïᓽ#7¶I᥅¿'Ḅ¦ìVòḄWXÊÊḄWXᓄhᑁQ=ãᐸ)Aóô¶I᥅¿'sãóôl$õö☢ã7¶IḄ÷ø(ᡈã7ú)஺

15^12᝞t5-13ᡠwl$ãa%0.2kgḄ«ᳫᵨe60.22mḄÿ
ᙠ30°Ḅᐝ☢☢ᙠḄ!ᵨ#%5-13)ᚖ+,☢ᔣḄឤ/42.2N஺ᙠ/5Ḅ!ᵨ67ᳫᔣ9:;ᳫ,5<ᔣḄ=>K@AᓄḄᐵDE%ឤG),JK#L@7ᳫM#NOPQJK#L@R#NSTOP…ᵫ+7ᳫW@ḄᨵYឋ[/\!ᵨ]2s7ᳫSTᨬ`#NOP,aRᑖcde10m/shih(1)ᨬ`#NOP`;ᳫḄklmn(2)ᨬ`#NOPoᡂ;ᳫḄlmn(3)᦮)OPKrDstᜫḄvwx஺ூz⚪௃}⚪Kr~z⚪⌕ᑮ;ᳫ,F<ᔣ9:ḄᱯlḄᒴkl9:ᑣ7;ᳫSTᨬ`#NOPᐸlm=>ai]஺ூ᪆௃(1)7;ᳫ᦮9ᵨMhF-2mgsm30°a==05ffl/y22m(2);ᳫ,5<ᔣḄ=>@AᓄḄᐵDEs=kt?(kឤG),ᡠ¢ᒴkl9:ᑣᓃ=aᱏlm/s஺(3)᪷¨©xªᳮᨵ:^E=F(s+-)-2mgsin30°-2ximv,2ᐸs=±ᐭᦪ¨-2L

16ூµ¶௃}⚪·¸¹º»⌕ᢕ½ᐸḄᐵ¾᝞ᑖ᪆ÀÁ;ᳫ,F<ᔣḄ9:ÂÃஹᑖ᪆ÀÁᐰKrḄxGÆᓄᐵDÇÈ/FÉ©ÊὑḄxGÆᓄ7;ᳫḄÌ/Íx:x¢Î7;ᳫOPÏTḄÐGᯠ`ᵫxGÒឤaÓ}⚪஺