初三物理题(压强)!!!!!详细解题者,加分,谢谢!!!
\u521d\u4e09\u7269\u7406\u538b\u529b\u548c\u538b\u5f3a\u600e\u4e48\u7b97\u6c42\u8be6\u7ec6\u89e3\u7b54\u89e3\uff1a\u5bf9\u5730\u9762\u7684\u538b\u529bF=(G1+G2)=(m1+m2)g=(48kg+12kg)X10(N/kg)=600N
\u603b\u63a5\u89e6\u9762\u79ef\u4e3a40\u5e73\u65b9\u5398\u7c73\uff1d0.040m²
\u5bf9\u5730\u9762\u7684\u538b\u5f3aP=F/S=²N/0.040m²=15000Pa
\u5982\u679c\u7b49\u9ad8\u5219\u539f\u6765\u7684P\u7532=P\u4e59\u6240\u4ee5
\u8fd9\u662f\u4e2a\u4e0d\u7b49\u9ad8\u7684\u5706\u67f1\u4f53\uff01\uff01\uff01\u4e14\u9ad8\u5ea6\u7532<\u4e59\uff0c\u8fd9\u662f\u6761\u4ef6\uff0c\u662f\u5417\uff1f
\u6839\u636eP=Mg/S\u7684\u5b9a\u4e49\uff0c\u5f53S\u4e0d\u53d8\u65f6\uff0cP\u968fMg\u6210\u6b63\u6bd4\u4f8b\u53d8\u5316\uff0c\u7531\u4e8e\u662f\u5706\u67f1\u4f53\uff0c\u5219\u968f\u9ad8\u5ea6H\u6210\u6b63\u6bd4\u4f8b\u53d8\u5316\u3002
\u5219\u8bbe\u539f\u6765\u7532\u9ad8\u4e3aH\u7532\uff0c\u539f\u6765\u4e59\u9ad8\u4e3aH\u4e59\uff0c\u622a\u53bb\u7684\u76f8\u540c\u9ad8\u5ea6\u4e3ah\uff0c\u539f\u59cb\u5bf9\u5730\u538b\u5f3a\u5206\u522b\u4e3aP\u7532\u548cP\u4e59\uff0c\u76f8\u540c\u65f6\u7684\u538b\u5f3a\u4e3ap
p=P\u7532*\uff08H\u7532-h\uff09=P\u4e59*\uff08H\u4e59-h\uff09
\u7531\u4e8eH\u7532<H\u4e59\u5219\uff1a\uff08H\u7532-h\uff09<\uff08H\u4e59-h\uff09
\u6240\u4ee5P\u7532/P\u4e59>1,
\u539f\u6765\u5bf9\u6c34\u5e73\u5730\u9762\u7684\u538b\u5f3aP\u7532>P\u4e59
\u8fd9\u7c7b\u9898\u4e3b\u8981\u662f\u627e\u51fa\u538b\u5f3a\u4e0e\u538b\u5f3a\u4e4b\u95f4\u7684\u5173\u7cfb\uff0c\u8fd9\u91cc\u662f\u901a\u8fc7\u7ebf\u6027\u6bd4\u4f8b\u5173\u7cfb\u505a\u51fa\u6bd4\u8f83
G=F总-G木=600N-12N=588N
m=G÷g=588N÷9.8N/Kg=60Kg
答:中学生的质量为60千克
F人=G=588N S鞋=0.02m²×2=0.04m²
P人=F人÷S鞋=588N÷0.04m²=14700Pa
答他站立时对木板的压强为14700帕
(1)P=F/S
6000=F/0.1
F=600N
F人=600-12=588N
G=mg
m=588/9.8=60kg
(2)P=F/S
P=588/0.04
P=14700Pa
OK就是这样吧
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