一辆汽车以36km/h的速度匀速驶向前面的山崖,司机鸣笛后 4s听到了回声,求听到回声时距山崖的距离.

\u4e00\u8f86\u6c7d\u8f66\u4ee536km/h\u7684\u901f\u5ea6\u5300\u901f\u5411\u524d\u9762\u7684\u5c71\u5d16\uff0c\u53f8\u673a\u9e23\u7b1b\u540e4S\u542c\u5230\u4e86\u56de\u58f0\uff0c\u6c42\uff1a\u542c\u5230\u56de\u58f0\u65f6\u6c7d\u8f66\u5c45\u5c71\u5d16\u7684\u8ddd\u79bb\uff1f

v=36km/h=10m/s
4\u79d2\u5185\uff0c\u58f0\u97f3\u4f20\u64ad\u7684\u8ddd\u79bb S\u58f0=v\u58f0t=340m/s\u00d74s=1360m
4\u79d2\u5185\uff0c\u8f66\u8d70\u7684\u8ddd\u79bb S\u8f66=v\u8f66t=10m/s\u00d74s=40m
\u56e0\u6b64\uff0c\u542c\u5230\u56de\u58f0\u65f6\uff0c\u8f66\u5230\u5c71\u5d16\u7684\u8ddd\u79bb S=\uff08S\u58f0-S\u8f66\uff09/2=\uff081360m-40m\uff09/2=660m

\u89e3\uff0c36KM/h=10M/s\u56db\u79d2\u540e\u9a91\u8f66\u884c\u9a76\u4e864*10=40M
\u2235\u58f0\u97f3\u5728\u7a7a\u6c14\u4e2d\u4f20\u64ad\u901f\u5ea6\u4e3a340M/S
\u22344\u79d2\u58f0\u97f3\u4f20\u64ad\u4e86340X4=1360m
\u8bbe\u542c\u5230\u56de\u58f0\u65f6\u8ddd\u79bb\u5c71\u5d16\u7684\u8ddd\u79bb\u4e3ax\uff0c\u6c7d\u8f66\u9e23\u7b1b\u65f6\u8ddd\u79bb\u4e3aY\uff0c\u6839\u636e\u4ee5\u4e0a\u6761\u4ef6\u90a3\u4e48\u6211\u4eec\u53ef\u4ee5\u5efa\u7acb\u65b9\u7a0b\uff1a
X+y=1340
y-x=40
\u89e3\u8fd9\u4e2a\u4e8c\u5143\u4e00\u6b21\u65b9\u7a0b\u7684x=650, y=690
\u7b54\uff1a\u6c7d\u8f66\u9e23\u7b1b\u65f6\u8ddd\u79bb\u5c71\u5d16690m\uff0c\u542c\u5230\u56de\u58f0\u8ddd\u79bb\u5c71\u5d16650m


\u5e0c\u671b\u53ef\u4ee5\u5e2e\u5230\u4f60\uff0c\u671b\u91c7\u7eb3\u3002

您好，36KM/H=10M/S，所以汽车的速度为10M/S,而声音在空气中的传播速度约为340M/S，4S内汽车前进了40M，声音传播了340X4=1360M，设听到回声时距山崖Xm，可得2X+40=1360，解得X=660M
球采纳~

v车＝36km/h=10m/s

S声－S车＝2L

v声t－v车t=2L

340 x 4－10 x 4=2L

L=660(m)

听到回声时距山崖660米

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