13、如图11所示，平板小车C静止在光滑的水平面上。现在A、B两个小物体（可视为质点），小车C的两端同时...
\u5982\u56fe\u6240\u793a\uff0c\u5e73\u677f\u5c0f\u8f66C\u9759\u6b62\u5728\u5149\u6ed1\u7684\u6c34\u5e73\u9762\u4e0a\uff0e\u73b0\u6709A\u3001B\u4e24\u4e2a\u5c0f\u7269\u4f53\uff08\u53ef\u89c6\u4e3a\u8d28\u70b9\uff09\uff0c\u5206\u522b\u4ece\u5c0f\u8f66C\u7684\u4e24\u7aef\u540c\u65f6\u6c34\uff081\uff09\u4ee5A\u3001B\u4e24\u7269\u4f53\u53ca\u5c0f\u8f66\u7ec4\u6210\u7684\u7cfb\u7edf\u4e3a\u7814\u7a76\u5bf9\u8c61\uff0c\u4ee5A\u7684\u521d\u901f\u5ea6\u65b9\u5411\u4e3a\u6b63\u65b9\u5411\uff0c\u7531\u52a8\u91cf\u5b88\u6052\u5b9a\u5f8b\u5f97\uff1a m?vA-mvB+0=3mv\uff0c\u89e3\u5f97\uff1av\uff1dvA?vB3\uff1d0.1m/s\uff0c\u65b9\u5411\u5411\u53f3\uff0e\uff082\uff09B\u5411\u5de6\u51cf\u901f\u52300\u65f6\u5411\u5de6\u7684\u4f4d\u79fb\u6700\u5927\uff0c\u5bf9B\u7531\u52a8\u80fd\u5b9a\u7406\u5f97\uff1a?\u03bcmgs2\uff1d0?12mv2B\u6240\u4ee5\uff1as2\uff1dv2B2\u03bcg\uff1d0\uff0e322\u00d70.1\u00d710m\uff1d0.045m\uff083\uff09\u8bbe\u5c0f\u8f66\u7684\u957f\u5ea6\u81f3\u5c11L\uff0c\u6839\u636e\u7cfb\u7edf\u80fd\u91cf\u5b88\u6052\u5f97 \u03bcmgL=12mv2A+12mv2B?12?3mv2 \u4ee3\u5165\u6570\u636e\u89e3\u5f97\uff0cL=0.21m\u7b54\uff1a\uff081\uff09A\u3001B\u3001C\u5171\u540c\u8fd0\u52a8\u7684\u901f\u5ea6\u4e3a0.1m/s\uff0c\u65b9\u5411\u5411\u53f3\uff1b\uff082\uff09B\u7269\u4f53\u76f8\u5bf9\u4e8e\u5730\u5411\u5de6\u8fd0\u52a8\u7684\u6700\u5927\u4f4d\u79fb\u662f0.045m\uff1b\uff083\uff09\u5c0f\u8f66\u7684\u957f\u5ea6\u81f3\u5c11\u662f0.21m\uff0e
\uff081\uff09 A \u3001 B \u3001 C \u5171\u540c\u8fd0\u52a8\u7684\u901f\u5ea6 v ="0.1" m/s\u65b9\u5411\u5411\u53f3?\uff082\uff09? B \u5bf9\u5730\u5411\u5de6\u6700\u5927\u4f4d\u79fb s max ="4.5" cm?\uff083\uff09\u5c0f\u8f66\u7684\u957f\u5ea6 L ="21" cm? \uff081\uff09\u8bbe A \u3001 B \u3001 C \u8d28\u91cf\u90fd\u4e3a m \uff0c\u5171\u540c\u8fd0\u52a8\u901f\u5ea6\u4e3a v \uff0c\u4ee5\u5411\u53f3\u4e3a\u6b63\u65b9\u5411\uff0e?\u52a8\u91cf\u5b88\u6052 mv A + m (\uff0d v B )=3 mv ?\u4ee3\u5165\u6570\u636e\u5f97 v ="0.1" m/s\u65b9\u5411\u5411\u53f3?\uff082\uff09\u5f53 B \u5411\u5de6\u8fd0\u52a8\u901f\u5ea6\u4e3a\u96f6\u65f6\uff0c\u6709\u5411\u5de6\u6700\u5927\u4f4d\u79fb\uff0e? B \u5411\u5de6\u8fd0\u52a8\u52a0\u901f\u5ea6\u4e3a a = = \u03bcg ="1" m/s 2 ? B \u5bf9\u5730\u5411\u5de6\u6700\u5927\u4f4d\u79fb s max = ="4.5" cm?\uff083\uff09\u8bbe\u5c0f\u8f66\u957f\u4e3a L \uff0c\u4f9d\u529f\u80fd\u5173\u7cfb? \u03bcmgL = mv A 2 + mv B 2 + \u00d73 mv 2 ?\u4ee3\u5165\u6570\u636e\u5f97 L ="21" cm?
(1)A、B、C总动量守恒mVA－mVB=(3 m)*V
V=(VA－VB) / 3=(1.2－0.6) / 3=0.2 m/s
(2) VB^2=2*μg*SB
0.6^2=2*0.1*10*SB
SB=0.18米
(3)车长度L
(m*VA^2 / 2)＋(m*VB^2 / 2)=μ*mg*L＋(3m*V^2 / 2)
得 L=0.84米
1. 三者动量守恒m*Va-m*Vb=3mV，共同速度V=0.2m/S，与A的初速度方向相同
2. B相对小车运动，水平方向只有摩擦力，产生的加速度-ug=-1m/S2，相对于地面最大位移为速度为0时，t=VB/ug=0.6S,位移为1/2*VB*S=0.18m
系统，动量守恒，3Mv＝MvA-MvB v=0.2m/s
B为0前，小车静，
SB＝vB^2/2μg
=0.18m
SA=(vA^2-v^2)/(2μg)
=0.7m
小车a,
a=μg/2
=0.5m/s^2
S=v^2/2a
=0.04m
L=SA+SB-S
=0.74m
绛旓細(1)A銆丅銆丆鎬诲姩閲忓畧鎭 mVA锛峬VB=(3 m)*V V=(VA锛峍B) / 3=(1.2锛0.6) / 3=0.2 m/s (2) VB^2=2*渭g*SB 0.6^2=2*0.1*10*SB SB=0.18绫 (3)杞﹂暱搴 (m*VA^2 / 2)锛(m*VB^2 / 2)=渭*mg*L锛(3m*V^2 / 2)寰椼L=0.84绫 ...
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绛旓細锛3锛灏忚溅鐨勯暱搴 L ="21" cm? 锛1锛夎 A 銆 B 銆 C 璐ㄩ噺閮戒负 m 锛屽叡鍚岃繍鍔ㄩ熷害涓 v 锛屼互鍚戝彸涓烘鏂瑰悜锛?鍔ㄩ噺瀹堟亽 mv A + m (锛 v B )=3 mv ?浠ｅ叆鏁版嵁寰 v ="0.1" m/s鏂瑰悜鍚戝彸?锛2锛夊綋 B 鍚戝乏杩愬姩閫熷害涓洪浂鏃讹紝鏈夊悜宸︽渶澶т綅绉伙紟? B 鍚戝乏杩愬姩鍔犻熷害涓 a = ...
绛旓細(1)A銆丅銆丆鎬诲姩閲忓畧鎭 mVA锛峬VB=(3 m)*V V=(VA锛峍B) / 3=(1.2锛0.6) / 3=0.2 m/s (2) VB^2=2*渭g*SB 0.6^2=2*0.1*10*SB SB=0.18绫 (3)杞﹂暱搴 (m*VA^2 / 2)锛(m*VB^2 / 2)=渭*mg*L锛(3m*V^2 / 2)寰椼L=0.84绫 ...
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