|
|
????????????????
???????????
?1 ??????????m=510kg?????????????????s =5.3210m?????????v =60m/s?????????????????????0.02??k=0.02????????????
?2 ???m=2kg?????????H=2m???????????????????h=5cm??????????????????????g?10m/s2?
2-7-2
?3 ????0.3????????????????6m/s???????????????????????????????????????????????????????????v???????????????W?? ?
A .?v=0 B. ?v=12m/sC. W=0 D. W=10.8J
?4 ?h???????v0??????????????????????????????? A. v0?2ghB. v0?2gh C. 2v0?2gh D. 2v0?2gh 3
?5 ???? m???????l??????O?????????F?????????P????????Q????2-7-3??????F???????
A. mglcos? B. mgl(1?cos?)C. Flcos?D. Flsin?
2-7-3
?6 ??????????????????O???????
??????????????????F???????R????
?????8F??????????R?2????????????
?????????????????________.
?7 ??2-7-4?????????????????????v0?2m/s?????????????????????30??????m?l0kg?????????????????????h?2m?????????????????????3?g?2
10m/s2?
(1) ?????????????????????
(2) ???????????h?2m???????????????????
2-7-4
?8??4???AB?1/4????????R=0.8m?BC???????S=3m?BC????????=1/15?????m=1kg?????A????????C????????????AB?????????????
?9??????????????8kg????????????120N???????????1 200W??????????????????????90m?????????90m?????????????????????????g?10 m/s2?
?10?????????h??????????????????????????????????????????S???2-7-6??????????????????????????????????????????????
2-7-6
?11 ????H?????????????????????????????k?k<1??,????????????????????????
?1? ??????????????????????????
?2? ????????????????????????????
?12??????h???????????m?????????s?????????????
?13?????????l?????????O??????????m??????????????????????????v0??????????????????????P?v0??????
?14 ????????????v=20m/s???????????=1.4kg/m3?????????S=20m2????50%?????????????????????????????????????
2-7-7
?15 ???M????d???????????????????????????????????????????m????????V0????????????????????????????????????????????V0?????????????????????
???1??????????
?2????????????????????????????????
?16??2-7-19??????????A?B???B???????????F?B?1m?s????P???Q,P?Q??????????????1=37??2=60.??????????h=2m???mA=10kg?mB=20kg?????????????????
2??F???(?sin37=0.6?g?10m?s)
?????
1???????????????????????????G????N????F ???f ?????2-7-1??
N
f F
2-7-1
????????WG=0?WN=0?WF=Fs?Wf=-kmgs.
?????????0?????12mv 2
12??????? Fs?kmgs?mv?02
v2
?????? F?kmg?m?1.8?104N2s2??????????????????????????
??????????????????
mg(H?h)?Fh?0?0?
????????????
F?H?h2?0.05?mg??2?10N=820N? h0.05
3??? ????????????????????v=vt-(-v0)=12m/s,??????
112W??EK?mvt2?mv0?0 22
???BC
4??? ?????????????????????????????????
mgh?
?????????????v?1212mv?mv0? 222v0?2gh?
?????C?
5??? ??????P????????Q?????????????????????????????F=mgtan?????????????F??????????????W= Flcos???????????????????
???????????????????????????????????????????W?????????mgl(1?cos?)?
????????????????0????????W?mgl(1?cos?)=0?
W= mgl(1?cos?)?
?????B?
6?3FR 2
??????? ???????
??????
????
????????????????????
1????????????????????????,?????????? ?
A????????????????????????????
B?????????????????????????
C?????????????????????????
D??????????????????
2?????????? ?
A??????????????????????
B????????????????????
C?????????????????????
D??????????????????????????
3????????????????????????????????????????
A??????? B????????
C?????????? D?????????????
4?????????????????????????????????
A????????s???
B????????s??????
C????????t???
D??????????????
5?????????v????????????s??????????????????????????v/2?????????????????
A?sB?s/2 C?s/2 D?s/4
6?????A?B?????mA?mB=2?1???????????????????????????????????????????????
A?sA?sB=2?1 B?sA?sB=1?2C?sA?sB=4?1D?sA?sB=1?4
7????m??????????v0????????????????L?????????????2m???????2v0???????????????????????
A?LB?2L C?4L D?0.5L
8?????????????????????v0???????????????????????????????????????????????
A??????B??????C??????D??????
9???????h?????????m???????????v0???????????v??g?????????????????????????????
1211122mv?mv0 B?mv2?mv0?mgh 2222
11212122C?mgh?mv0?mv D?mgh?mv?mv0 2222A?mgh?
10????????????????????????????????????????????????????????????
2222A?sin? B?cos? C?tan? D?cot?
11?????1kg????20m/s?????????????????????16m/s?????????????????????
A?200JB?128JC?72J D?0J
12?????1kg??????????????1m?????????2m/s?????????????
A???????12J B?????????12J
C?????????2J D?????????10J
13???A?B?????????mA =1kg?mB =2kg?B?????3N
???????A?B?????4m???1?????????B?A?
??????
?
1
A?4J B?12J C?0 D?-4J
14??????100N??????????????0.6kg?????15 m/s?????20m???????????????????
A?67.5J B?2000JC?1000J D?0J
15??????m???????L??????O?????????F????
?????P???????Q????2??????F?????? A?mgLcos? B?mgL(1-cos?)C?FLsin? D?FLcos?
????? 16???3?????????????m????????F??
???????A?????B???????F????????
?????? ????????????????????
??????????2m?????????A???B?????
??F?????? ???????????????B?
???????? ??????????????????
??????????????????????????????
????? ?? ?????????????????????????
17???????????M??????V?????????????H????????????????????? ??????????????????????
18????m??????????????????????????????????????????????????????????????????????????????s?????????? ?
?????
20??????m=2kg???????H=2m????????????h=5cm???
2??????????????????g?10m/s?
21????m?????????????????????4???A???????A???0?????????????????R????A??????????????2.5mg?????????????????
????
??????????????????
1?????????A???????B???1????????????? ?
A??????????????
B???????????????????
C???????????
D???????
2???2??????m???????h?????????
??A???????B??????????????????
????A???????C??????????? ?
A?mgh?B?2mgh?
C?3mgh? D???????????
3???????????????2m?????????????????????????????0.5m???????????????????????????? ?
A?2?? B?5?? C?8?? D?10??
4????????F?????????????????????L???F???????3L????????????????????????f?????Ek?? ?
FF?Ek=4FL? B?f??Ek=FL? 33
FFLF3FLC?f??Ek?? D?f??Ek?? 4344A?f?
5????1kg????????????????????????
???????????????3???g=10m/s2???????
???? ?
A???????????????0.5?
B???????????????0.2?
C??????????4s?
D??????????2.5s?
6???????????????????O???????????????
??????????F???????R?????????8F??????
????R?2?????????????????????????????
?????? ?
A?4FR?B?31FR? C?FR? D?FR? 22
7???5??????100J???????????????????
??????????M????????80J????????32J?
???????????????? ?
A?20J? B?48J? C?60J? D?68J?
8????m??????????????????????R???????????????????????????????????????????????7mg??????????????????????????????????????????????? ?
A?
111mgR?B?mgR? C?mgR? D?mgR? 432
9??????ABCD???????????????BC???
??????BC??????BC?????????d = 0.50m?
???????h = 0.30m??A???????m?????
????????????????????????BC???
???????????? 0.10??????????????
???????????B??????
A?0.50m B?0.25m C?0.10mD?0
?????
10???6???mA=4kg?A????????=0.2???????mB=1kg?B????h=0.8m?
2A?B??????????A?????????g?10m/s???
?1?B???????
?2?B????A???????????
???????????
?????
?????
1?A 2?AB 3?D 4?AD 5?D 6?B 7?C 8?D 9?C10?C11?C12?ACD
13?A14?A15?B
?????
16???????????????? 17?11mv2?mgH?mv218??mgs 22
?????
19?????????????????????
?W?=mg?H+h?fh
???????mg?H+h?fh=00 ?f?mg(H?h) ?????f=820N h
v2
20????B??N?mg?m R
?mvB2=?N-mg?R=1.5mgR 132mvB?0.75mgR?mgR 24
31???????mgR?Wf?mgR ? Wf??mgR 44
1???????????mgR 4?
?????
?????
1?C 2?B 3?B 4?D 5?C 6?B 7?A 8?C 9?D
?????
10???????B????A?B???????????
??A?B??????????????????mBgh??mAgh?
v?1(mA?mB)v2 22(mB??mA)gh??????v=0.8m/s mA?mB
??A?????????????s????????
1v22??mAgs?0?mAv??s???????s=0.16m 22?g
?????????????????
???????
1???????????????3m???M=10kg?????F=50N??????????v0=5m?S??????????????????????m=3kg????(?????)??????????????????L=1m????????????????????????????????lm?????????????????????(g?10m?s2)? (1)????????????? (2)??????????????
(3)??????????????????????????
2?????????
1
??AB???R?0.8m???????????????M=2kg4
??????????????????CD????B??????????B?C???????L=1m??H=0.2m????????m=1kg????????????????A??????????????B???????????????????????????????x?0.2m?????????v?1m/s?? ?1?????B??????????? ?2?????????????? ?3?????????????
?4??????????????????
3??????????CD??????L1=2m??M????????M??????????????????????M????????????????AB?s=3m???????AFE??????????????R=0.4m???????AB???A????M???????L=2m?????????????u0=8m/s?????????????????????????????????????????????????u1=0.05????????????AB??????u2=0.1,????m=1kg?
2
?g=10m/s?
?1???????????????A????;
?2????????????????E??????????E??????????A????;???????????
4. ?????????????????M=2kg??????????????????????????m=1kg?????A??????????A??????????
2
?h=0.6m?????????t=1s??????????v =1m/s??????g=10m/s???
?1???????????
(2) ??????????????????
(3) ?????????????????????
???????????
1. ???1?????????????????????f???????
F?f ?
f??Mg ?
????????
??0.5??2????????????????????mg
??????
[??:Zxxk.Com]
??????????????v1???????????????????????
??mgL?2?mgL?
112Mv12?Mv0 ? 22
???????
v1?4m/s ?
?3????????????????????????????3?mg
??????????????????????????x??????????
1
?3?mgx?0?Mv12 ?
2
????????
x?
16
m?1.78m? 9
???????2????5?,??4??????1?? ???????????????????????????? ?2????????????????????mg?
?????????????????????????a1?a2?????????
???????????????v1?v2???????????????? a1??
?mg
M
??1.5m/s2
?
?
[??:?_?_?Z_X_X_K]
v1?
m/s
2?mga2??3?m/2s?
M
v2??4m/s?
[??:???]
?3?????????????????????????????3?mg?
????????????????????a3????????????????
????????x
a3??
???????????????????????
2
v216
? x???m?1.78m
2a39
3?mg
??4.5m/s2?M
??????????2????3??????1??
3.?16?????1????????????????1????????
??1(m?M)gl?
112
(M?m)?12?(M?m)?0 2? 22
????A?????u2????????
??2mg(s?L1)?
1
m?21?2?? 2
2?2
?????????
FN?MG?m
R2?
???FN=140N???????????????A???????140N????????1??
?2?????????????????????????u3????
112m?2?m?32?mg2R2? 22
??:?3?6m/s?gR?2m/s2?
????????????? ?x??3t1?
2R?
12
gt2? 2
???x=2.4m1?
4??18?? (1)??? Ff?Ma12?
???????? v?a1t2? ?? Ff?2N1? (2)??? ?Ff?ma2 2? ?????????????v0?
[??:Zxxk.Com]
??? v?v0?a2t2? ?? v0?3m/s
?????????????????
mgh?Wf?
12
mv02?2
[?????ZXXK]
????????????
Wf?mgh?
12
mv0?1.5J2? 2
12
a1t2? 2
(3)t=1s??????s1?
1
?????????s2?v0t?a2t2 2?
2
???????????L?s2?s1?1.5m1?
????????????????
?????http://www.850500.com/news/68020.html
?????,??! |
|
发表于 2019-9-13 23:46:11