物体静止在斜面上,以下的几种分析中正确的是( )
A．物体所受到静摩擦力的反作用力是重力沿斜面的分力
B．物体所受重力沿垂直斜面的分力就是物体对斜面的压力
C．物体所受重力的反作用力就是斜面对它的静摩擦力和支持力这两个力的合力
D．物体所受支持力作用就是物体对斜面的压力
答案：D
作用力和反作用力一定是同种性质的力,分别作用在两个物体上,物体受到静摩擦力的反作用是物体对斜面的摩擦力,所以A错;物体受重力沿垂直斜面的分力在数值上等于物体对斜面的压力,重力是地球对物体的力,压力是物体对斜面的力,所以B错;物体受到地球的反作用力是物体对地球的吸引,所以C错;因此此题选D,此题考查力､作用力和反作用力,作用力和反作用力有个明显的特点,就是它一定要体现A对B,B对A,如果不满足这个模式,那就不是了.
| 完型填空。 | ||||
| Have you heard of Zhou Yang? She is now well known __1__ an excellent short track speed skater (短道速滑运动员). Zhou Yang is not an overnight __2__. She was born in a poor family in Changchun on June 9th, 1991 and started __3__ at the age of 8. She fell in love with the __4__ at once when she put on her skate shoes to train for the first time. Soon her talent (天分) for short track speed skating was __5__. Zhou Yang trained hard and made her way into the national team __6__. In the world championships (锦标赛) in 2008, Zhou Yang set a world record in the 1,500m event. Zhou Yang __7__ herself again at the 2010 Winter Olympics. Her performance gave China the __8__ gold medal in the women's 1,500 meters in the Winter Olympics — China had never won the event before. "Winning 1,500m is my dream, __9__ I still have one more dream, winning the relay (接力) competition," Zhou Yang said. Her "one more dream" __10__ when she and her teammates won the women's 3000m short track relay with a new world record. | ||||
|
