(2012?盐城三模)如图所示,置于竖直平面内的AB光滑杆,它是以初速为v0,水平射程为s的平抛运动轨迹制成 求南京盐城2012届高三三模物理选择题4、7解析
\u5982\u56fe\u6240\u793a\uff0c\u7f6e\u4e8e\u7ad6\u76f4\u5e73\u9762\u5185\u7684AB\u5149\u6ed1\u6746\uff0c\u5b83\u662f\u4ee5\u521d\u901f\u4e3av 0 \uff0c\u6c34\u5e73\u5c04\u7a0b\u4e3as\u7684\u5e73\u629b\u8fd0\u52a8\u8f68\u8ff9\u5236\u6210\u7684\uff0cA\u7aef\u4e3a\u629b\u51fa\u70b9C \u8bd5\u9898\u5206\u6790\uff1a\u636e\u9898\u610f\uff0c\u5c0f\u7403\u53d7\u5230\u91cd\u529bG\u548c\u652f\u6301\u529bN\uff0c\u6240\u4ee5\u5c0f\u7403\u7531\u9759\u6b62\u4ece\u5149\u6ed1\u6746\u4e0a\u6ed1\u4e0b\u7684\u8fd0\u52a8\u4e0d\u662f\u5e73\u629b\u8fd0\u52a8\uff0c\u5219\u5c0f\u7403\u5728\u6c34\u5e73\u65b9\u5411\u7684\u5206\u901f\u5ea6\u4e5f\u662f\u53d8\u5316\u7684\uff0c\u6240\u4ee5\u5c0f\u7403\u5728\u6c34\u5e73\u65b9\u5411\u7684\u5206\u901f\u5ea6\u4e0d\u7b49\u4e8ev 0 ,A\u9009\u9879\u9519\u8bef\uff1b\u5c0f\u7403\u7684\u8fd0\u52a8\u65f6\u95f4\u4e5f\u4e0d\u7b49\u4e8et="s/" v 0 ,\u6240\u4ee5B\u9009\u9879\u9519\u8bef\uff1b\u5c0f\u7403\u673a\u68b0\u80fd\u5b88\u6052\uff0c\u6709mgh=mv 2 /2,\u7531\u4e8e\u5149\u6ed1\u6746\u662f\u6309\u7167\u5e73\u629b\u8fd0\u52a8\u7684\u8f68\u8ff9\u5236\u5b9a\u7684\uff0c\u6240\u4ee5\u8f68\u8ff9\u9075\u5faa\u5e73\u629b\u8fd0\u52a8\u89c4\u5f8b\uff0c\u5219\u6709tan\u03b8="2tana," a\u662f\u4f4d\u79fb\u504f\u5411\u89d2\uff0c\u03b8\u901f\u5ea6\u504f\u5411\u89d2\uff0ctan\u03b8=v y /v x , v y = \uff0cv x = v 0 \uff0c\u800ctan\u03b1=y/x\uff0cy=gt 2 /2,x=s,\u8054\u7acb\u6c42\u5f97h= \uff0c\u5408\u901f\u5ea6v= \uff0cC\u9009\u9879\u6b63\u786e\uff1b\u5c0f\u7403\u91cd\u529b\u7684\u529f\u7387\u4e3aP="mgvsin\u03b8=" \uff0c\u6240\u4ee5D\u9009\u9879\u9519\u8bef\u3002
4\u3001\uff081\uff09\u7531\u673a\u68b0\u80fd\u5b88\u6052\uff1amgh=1/2mv2,\u89e3\u5f97v=\u6839\u53f7\u4e0b2gh
\uff082\uff09\u5728\u5e73\u629b\u8fd0\u52a8\u4e2dt=s/v0
h=1/2gt2=1/2gs2/v02
\u89e3\u5f97:v=gs/ v0
7\u3001\uff081\uff09aA==2aB \u7531\u4e8e\u53d7\u529b\u4e3a\u4f5c\u7528\u529b\u4e0e\u53cd\u4f5c\u7528\u529b\uff0c\u6240\u4ee52mA=mB
\uff082\uff09\u52a0\u5165c\u540e\uff1a
\u7b2c\u4e00\u79cd\u60c5\u51b5\uff1aa\u4e0ec\u95f4\u7684\u529b\u5c0f\u4e8ea\u4e0eb\u95f4\u7684,\u8bbec\u5e26\u7535\u91cf\u4e3ax\u636e\u9898\u53ef\u77e5\u4e3a\u6b63\uff1a\u7531aA==aB\u5f97(k2q2/r2- k2xq2/(r/2)2)/ mA=(k2q2/r2+ k x q2/(r/2)2)/2 mA,,\u89e3\u5f97x=0.1
\u7b2c\u4e00\u79cd\u60c5\u51b5\uff1aa\u4e0ec\u95f4\u7684\u529b\u5927\u4e8ea\u4e0eb\u95f4\u7684,\u8bbec\u5e26\u7535\u91cf\u4e3ax\u636e\u9898\u53ef\u77e5\u4e3a\u6b63\uff1a\u7531aA==aB\u5f97(k2xq2/(r/2)2-k2q2/r2)/ mA=(k2q2/r2+ k x q2/(r/2)2)/2 mA,,\u89e3\u5f97x=0.5
\u5e73\u65b9\u5728\u8fd9\u91cc\u6ca1\u6cd5\u663e\u793a\uff0c\u4f60\u6839\u636e\u516c\u5f0f\u8003\u8651\u5c31\u597d\u4e86
B、以初速为v0平抛物体的运动,其水平分运动是匀速直线运动,时间为
S |
v0 |
S |
v0 |
C、以初速为v0平抛物体的运动,根据分位移公式,有:
h=
1 |
2 |
S=v0t ②
vx=v0 ③
vy=gt ④
解得:h=
gS2 | ||
2
|