初中科学九年级上册第3节能量转化量度浙教知识点练习含解析八

初中科学九年级上册[第3节能量转变量度]浙教版知识点练习[含剖析]八初中科学九年级上册[第3节能量转变量度]浙教版知识点练习[含剖析]八初中科学九年级上册[第3节能量转变量度]浙教版知识点练习[含剖析]八最新教育资料精选2021年精选初中科学九年级上册[第3节能量转变的量度]浙教版知识点练习[含答案剖析]八第1题【单项选择题】在甲、乙两图中，甲图地面粗糙、乙图地面圆滑。质量分别为m，2m的两个物体在大小为F的恒力作用下，在力的方向上前进了相同的距离，那么以下结论正确的选项是( )A、甲图中F做的功小于乙图中F做的功B、甲图中F做的功等于乙图中F做的功C、甲图中F做的功大于乙图中F做的功D、甲图中F做功的功率必然大于乙图中F做功的功率大【答案】：【剖析】：第2题【单项选择题】以以下图，用力击打一摞棋子中间的一个，该棋子会飞出去，以下说法正确的选项是( )1/10最新教育资料精选A、飞出的棋子相对于其他棋子是静止的B、打击棋子时，打击力对棋子做了功C、上面的棋子落到原来地址下方的过程中，它的运动状态保持不变D、若是全部的力突然全部消失，在空中翱翔的棋子将保持静止状态【答案】：【剖析】：第3题【单项选择题】科学与人们的生活亲密相连，用所学科学知识判断，以下说法正确的选项是( )A、使用简单机械都能省力，也可以省功B、坐沙发比坐木凳愉快，利用了减小压力来减小压强的原理C、多吃水果、蔬菜可以补充维生素，维生素为人体生理活动供应能量D、通风橱是用排风扇将橱内废气直接排放到室外的装置，它是一种不完满的防污设施【答案】：【剖析】：2/10最新教育资料精选第4题【单项选择题】物体在一水平面上做直线运动，先在大小为F的水平推力作用下匀速前进了一段距离，接着在方向不变大小为2F的推力作用下连续前进了相同距离，以下说法正确的选项是( )A、整个过程重力对物体做了功B、前一段距离物体所受力合力为零C、后一段距离物体仍匀速运动D、前、后两段距离物体碰到的摩擦力不相等【答案】：【剖析】：第5题【单项选择题】南宁市某商场举行首届跑楼梯比赛，共有500多名选手参加.假设要比较参赛者的功率大小，需测出的物理量是( )A、登楼所用的时间B、参赛者的体重，所登楼层的高度C、参赛者的体重，所登楼层的高度以及登楼所用的时间D、参赛者的体重，所登楼层的高度，登楼所用的时间以及参赛者经过的行程3/10最新教育资料精选【答案】：【剖析】：第6题【填空题】在研究“汽车的速度〞的实验中，甲、乙两辆相同的汽车在同一水平川面上做直线运动的s﹣t图象如图所示．由图可知，甲车的动能______〔选填“大于〞、“小于〞或“等于〞〕乙车的动能；经过相同的时间，甲、乙两车牵引力做的功之比为______．〔空气阻力忽略不计〕【答案】：【剖析】：第7题【填空题】4/10最新教育资料精选以以下图的铁块重力G=4N，被吸附在竖直放置且足够长的磁性平板上，当他在竖直方向上拉力F=6N的作用下向上运动，那么铁块碰到的摩擦力为______N。铁块此时速度v与时间t的关系图像如图乙所示，4s内拉力F做的功是______J。【答案】：【剖析】：第8题【填空题】一质量为牛的汽车坠入沼泽地，并且发动机出现了故障。以以下图，在电动机带动下用滑轮组把汽车拉出。在整个拉出过程中，汽车的运动可看作匀速直线运动，速度为，所受的阻力为2.4x10^4N，搬动的距离为4m。电动机的电源电压为380V，电流为50A，电动机供应的拉力F为10^4N。求这个过程中：滑轮组对汽车做的功是______J。5/10最新教育资料精选该电动机线圈发热损失的功率为______W。【答案】：无【剖析】：第9题【解答题】图甲是建筑长江大桥是使用起吊装置〔图中未画出〕的钢缆绳拉实在心圆柱体A距江面某一高度处沿竖直方向匀速下降，在下降到江底从前，向来保持的速度不变．图乙是A下降到江底从前钢缆绳对A的拉力F的随时间t变化的图象〔取江水的密度为ρ=1.0×10^3kg/m^3，g取10N/kg〕．求：<!--{cke_protected}{C}%3C!%2D%2D%5Bif%20gte%20mso%209%5D%3E%3Cxml%3E%0A%20%3Cw%3AWordDocument%3E%0A%20%20%3Cw%3AView%3ENormal%3C%2Fw%3AView%3E%0A%20%20%3Cw%3AZoom%3E0%3C%2Fw%3AZoom%3E%0A%20%20%3Cw%3APunctuationKerning%3E%3C%2Fw%3APunctuationKerning%3E%0A%20%20%3Cw%3ADrawingGridVerticalSpacing%3E7.8%20%E7%A3%85%3C%2Fw%3ADrawingGridVerticalSpacing%3E%0A%20%20%3Cw%3ADisplayHorizontalDrawingGridEvery%3E0%3C%2Fw%3ADisplayHorizontalDrawingGridEvery%3E%0A%20%20%3Cw%3ADisplayVerticalDrawingGridEvery%3E2%3C%2Fw%3ADisplayVerticalDrawingGridEvery%3E%0A%20%20%3Cw%3AValidateAgainstSchemas%3E%3C%2Fw%3AValidateAgainstSchemas%3E%0A%20%20%3Cw%3ASaveIfXMLInvalid%3Efalse%3C%2Fw%3ASaveIfXMLInvalid%3E%0A%20%20%3Cw%3AIgnoreMixedContent%3Efalse%3C%2Fw%3AIgnoreMixedContent%3E%0A%20%20%3Cw%3AAlwaysShowPlaceholderText%3Efalse%3C%2Fw%3AAlwaysShowPlaceholderText%3E%0A%20%20%3Cw%3ACompatibility%3E%0A%20%20%20%3Cw%6/10最新教育资料精选3ASpaceForUL%3E%3C%2Fw%3ASpaceForUL%3E%0A%20%20%20%3Cw%3ABalanceSingleByteDoubleByteWidth%3E%3C%2Fw%3ABalanceSingleByteDoubleByteWidth%3E%0A%20%20%20%3Cw%3ADoNotLeaveBackslashAlone%3E%3C%2Fw%3ADoNotLeaveBackslashAlone%3E%0A%20%20%20%3Cw%3AULTrailSpace%3E%3C%2Fw%3AULTrailSpace%3E%0A%20%20%20%3Cw%3ADoNotExpandShiftReturn%3E%3C%2Fw%3ADoNotExpandShiftReturn%3E%0A%20%20%20%3Cw%3AAdjustLineHeightInTable%3E%3C%2Fw%3AAdjustLineHeightInTable%3E%0A%20%20%20%3Cw%3ABreakWrappedTables%3E%3C%2Fw%3ABreakWrappedTables%3E%0A%20%20%20%3Cw%3ASnapToGridInCell%3E%3C%2Fw%3ASnapToGridInCell%3E%0A%20%20%20%3Cw%3AWrapTextWithPunct%3E%3C%2Fw%3AWrapTextWithPunct%3E%0A%20%20%20%3Cw%3AUseAsianBreakRules%3E%3C%2Fw%3AUseAsianBreakRules%3E%0A%20%20%20%3Cw%3ADontGrowAutofit%3E%3C%2Fw%3ADontGrowAutofit%3E%0A%20%20%20%3Cw%3AUseFELayout%3E%3C%2Fw%3AUseFELayout%3E%0A%20%20%3C%2Fw%3ACompatibility%3E%0A%20%20%3Cw%3ADoNotOptimizeForBrowser%3E%3C%2Fw%3ADoNotOptimizeForBrowser%3E%0A%20%3C%2Fw%3AWordDocument%3E%0A%3C%2Fxml%3E%3C!%5Bendif%5D%2D%2D%3E--><!--{cke_protected}{C}%3C!%2D%2D%5Bif%20gte%20mso%209%5D%3E%3Cxml%3E%0A%20%3Cw%3ALatentStyles%20DefLockedState%3D%22false%22%20LatentStyleCount%3D%22156%22%3E%0A%20%3C%2Fw%3ALatentStyles%3E%0A%3C%2Fxml%3E%3C!%5Bendif%5D%2D%2D%3E--><!--{cke_protected}{C}%3C!%2D%2D%5Bif%20gte%20mso%2021%5D%3E%0A%3Cstyle%3E%0A%20%2F*%20Style%20Definitions%20*%2F%0A%20table.MsoNormalTable%0A%09%7Bmso-style-name%3A%E6%99%AE%E9%80%9A%E8%A1%A8%E6%A0%BC%3B%0A%09mso-tstyle-rowband-size%3A0%3B%0A%09mso-tstyle-colband-size%3A0%3B%0A%09mso-style-noshow%3Ayes%3B%0A%09mso-style-parent%3A%22%22%3B%0A%09mso-padding-alt%3A0cm%205.4pt%200cm%205.4pt%3B%0A%09mso-para-margin%3A0cm%3B%0A%09mso-para-margin-bottom%3A.0001pt%3B%0A%09mso-pagination%3Awidow-orphan%3B%0A%09font-size%3A10.0pt%3B%0A%09font-family%3A%22Times%20New%20Roman%22%3B%0A%09mso-fareast-font-family%3A%22Times%20New%20Roman%22%3B%0A%09mso-ansi-language%3A%230400%3B%0A%09mso-fareast-language%3A%230400%3B%0A%09mso-bidi-language%3A%230400%3B%7D%0A%3C%2Fstyle%3E%0A%3C!%5Bendif%5D%2D%2D%3E-->圆柱体A下降过程中，重力的功率？圆柱体A的密度．<!--{cke_protected}{C}%3C!%2D%2D%5Bif%20gte%20mso%209%5D%3E%3Cxml%3E%0A%20%3Cw%3AWordDocument%3E%0A%20%20%3Cw%3AView%3ENormal%3C%2Fw%3AView%3E%0A%20%20%3Cw%3AZoom%3E0%3C%2Fw%3AZoom%3E%0A%20%20%3Cw%3APunctuationKerning%3E%3C%2Fw%3APunctuationKerning%3E%0A%20%20%3Cw%3ADrawingGridVerticalSpacing%3E7.8%20%E7%A3%85%3C%2Fw%3ADrawingGridVerticalSpacing%3E%0A%20%20%3Cw%3ADisplayHorizontalDrawingGridEvery%3E0%3C%2Fw%3ADisplayHorizontalDrawingGridEvery%3E%0A%20%20%3Cw%3ADisplayVerticalDrawingGridEvery%3E2%3C%2Fw%3ADisplayVerticalDrawingGridEvery%3E%0A%20%20%3Cw%3AValidateAgainstSchemas%3E%3C%2Fw%3AValidateAgainstSchemas%3E%0A%20%20%3Cw%3ASaveIfXMLInvalid%3Efalse%3C%2Fw%3ASaveIfXMLInvalid%3E%0A%20%20%3Cw%3AIgnoreMixedContent%3Efalse%3C%2Fw%3AIgnoreMixedContent%3E%0A%20%20%3Cw%3AAlwaysShowPlaceholderText%3Efalse%3C%2Fw%3AAlwaysShowPlaceholderText%3E%0A%20%20%3Cw%3ACompatibility%3E%0A%20%20%20%3Cw%3ASpaceForUL%3E%3C%2Fw%3ASpaceForUL%3E%0A%20%20%20%3Cw%3ABalanceSingleByteDoubleByteWidth%3E%3C%2Fw%3ABalanceSingleByteDoubleByteWidth%3E%0A%20%20%20%3Cw%3ADoNotLeaveBackslashAlone%3E%3C%2Fw%3ADoNotLeaveBackslashAlone%3E%0A%20%20%20%3Cw%3AULTrailSpace%3E%3C%2Fw%37/10最新教育资料精选AULTrailSpace%3E%0A%20%20%20%3Cw%3ADoNotExpandShiftReturn%3E%3C%2Fw%3ADoNotExpa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