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北京市某区物理模拟测试卷中有这样一道实验型试题,解法虽不怎么繁难,但解后反思,耐人寻味,发人深省.原题:在“验证牛顿第二定律”的实验中,当砂桶和砂的总质量m远小于小车(含砝码)的总质量M时,认为细线拉小车的力F’=mg,而实际受到的拉力为F,根据百分误差的定义式△=|(F’-F)/F|×100%可知,在中学学生实验误差允许范围内,如果小车的总质量(含砝码)M=0.8kg,则砂桶和砂的总质量最大不超过_kg.
There is such an experimental test item in a physical simulation test in a certain district of Beijing. Although the solution is not too complicated, it is introspective, intriguing, and thought-provoking. The original question: In the experiment of “Verifying Newton’s Second Law”, when the sand bucket and When the total mass m of the sand is much smaller than the total mass M of the trolley (including the weight), the force F’=mg of the thin wire pulling cart is considered, and the actual pull force is F, according to the definition formula of percent error Δ=|( F’-F)/F|×100% shows that if the total mass of the trolley (including the weight) M = 0.8 kg, the total mass of the sand bucket and the sand should not exceed _kg within the allowable range of experimental error of middle school students. .