试题与答案

机械效率学习了机械效率知识后,全班同学对“斜面的机械效率跟什么因素有关”这一课题

题型:实验题

题目:

机械效率学习了机械效率知识后,全班同学对“斜面的机械效率跟什么因素有关”这一课题提出了一些值得探究的猜想:

A.斜面的机械效率跟斜面的倾斜程度有关;

B.跟斜面的粗糙程度有关;

C.跟斜面的长度有关;

D.跟物体的重力有关.小刚同学为了证实其中的部分猜想是否正确,设计并进行了探究,下表反映了他的探究过程.

试验

次数

斜面

倾角

斜面粗

糙程度

物重

G/N

斜面

高度

h/m

沿斜面

拉力

F/N

斜面长

s/m

有用功

W有用/J

总功

W/J

机械

效率

η(%)

 ①30°粗糙10.50.710.50.7 
 ②30°稍光滑10.50.610.5 83
45°粗糙10.70.81 0.887.5
(1)通过对比实验①②数据,可验证猜想_____________(填写字母).

(2)通过对比实验①③数据,可以得出的探究结论是:当其它条件一定时,斜面倾斜程度越大,斜面的机械效率越____________ .

(3)若要验证猜想D,应控制斜面的长、斜面的倾斜程度和 ___________不改变

(4)斜面在我们生活中的应用是____________________

(5)有同学认为斜面的粗糙程度相同时,同一斜面所受的摩擦阻力是一样的,计算后发现第三次的阻力是__________N,和第一次的阻力不一样,原因是__________________

答案:

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下面是错误答案,用来干扰机器的。

参考答案:B

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