文档介绍：河南省2001年中考物理试题
of rural drinking water sources, protection of drinking water sources in rural areas by the end ，将塞子塞紧，通过塞子上的开口往瓶内打气，当塞子从瓶口跳起时，瓶中会出现雾，发生这一现象的原因是
of rural drinking water sources, protection of drinking water sources in rural areas by the end of the delimitation of the scope of protection, complete with warning signs, isolating network protection facilities
of rural drinking water sources, protection of drinking water sources in rural areas by the end of the delimitation of the scope of protection, complete with warning signs, isolating network protection facilities中学生学习网〔〕，海量中考资源免费下载！
of rural drinking water sources, protection of drinking water sources in rural areas by the end of the delimitation of the scope of protection, complete with warning signs, isolating network protection facilities
。
图3
11．作用在同一直线上的两个力，合力为12牛，假设其中一个力的大小为15牛，那么另一个力的大小为 。
12．把质量为250克，体积为300厘米3的金属球放入水中，静止时它受到的浮力为 。
二、选择题(每题2分，共16分)
以下各题均有四个答案，其中只有一个是正确的，将正确答案的代号字母填入题后号内。
13．以下实例中，通过热传递改变物体内能的是 ( )
A．钻木取火
B．两手相互摩擦使手变热
C．反复弯折铁丝，弯折处变热
of rural drinking water sources, protection of drinking water sources in rural areas by the end of the delimitation of the scope of protection, complete with warning signs, isolating network protection facilities
of rural drinking water sources, protection of drinking water sources in rural areas by the end of the delimitation of the scope of protection, complete with warning signs, isolating network protection facilities中学生学习网〔〕，海量中考资源免费下载！
of rural drinking water sources, protection of drinking water sources in rural areas by the end of the delimitation of the scope of protection, complete with warning signs, isolating network protection facilities
D．将食物放人冰箱内冷却
14．夏天，人站在吊扇下吹风有凉爽的感觉，如果把一支温度计也放在吊扇下吹风，温度计的示数将 ( )
A．升高 B．降低
C．不变 D．无法确定
15．把等质量的实心铁球和铝球分别挂在弹簧秤下并浸没于水中，那么 ( )
A．挂铁球的弹簧秤示数较大
B，挂铝球的弹簧秤示数较大
C．