2027新初三物理资料

新初三物理力学核心模型30题原创编制｜可打印使用—PAGE—新初三物理衔接系列PHYSICSTRANSITIONSERIES2026暑假·2027届适用成交信号延展产品022027届新初三物理力学核心模型30题

识别路径·分步得分·变式突破把八年级力学从“记公式”升级为“看见情境就知道用哪个模型”，专门解决会背不会做、过程分丢失和综合题卡壳。12张模型卡30题分层练分步评分错因复测覆盖运动、密度、受力、摩擦、压强、液体压强、浮力、功、功率、杠杆、机械效率与机械能；每个模型都有识别信号、路径、例题和易错提醒。适用对象2027届新初三学生｜家长陪练｜教师讲评｜培训机构测评交付特点结构完整·答案可核·评分可用·训练可执行·复盘可追踪

先学会识别：力学题的四步通法步骤要问自己的问题落笔动作1定对象研究谁？它处于什么状态？圈出研究对象，必要时画简图或受力图2找模型题目给了哪些量？求什么量？把“速度、压强、浮力、功率”等关键词写在题旁3列关系条件满足哪个定义式或规律？先写公式，再代入带单位的物理量4做检验方向、单位、数量级是否合理？写结论和单位；用极端情况或估算自检12张核心模型卡模型识别信号核心关系高频失分点01速度“多远、多长时间、平均快慢”v=s/t；平均速度=总路程/总时间休息和停留若计入全过程，时间必须加入02密度“质量—体积—材料判断”ρ=m/V体积单位先统一；空心物体不能直接用外形体积03受力与平衡“静止或匀速”“作用在谁上”同体、等大、反向、共线相互作用力与平衡力不能混为一谈04摩擦“粗糙、压力、相对运动趋势”滑动摩擦与压力、粗糙程度有关接触面积通常不是滑动摩擦大小的决定因素05固体压强“压力、受力面积、站立/平放”p=F/S水平面上F常等于G，但并非所有情境都等于06液体压强“深度、密度、同一水平面”p与ρ液、h有关深度是到自由液面的竖直距离07浮力“浸入、排液、示数差、浮沉”F浮=G-F示；F浮=ρ液gV排浸没后继续下沉，V排不变则浮力不变08功“有力且沿力方向移动距离”W=Fs提物水平走，竖直支持力通常不做功09功率“做功快慢、相同功比较时间”P=W/t功多不一定功率大，还要看时间10杠杆“支点、力臂、省力/费距离”F₁l₁=F₂l₂力臂是支点到力作用线的垂直距离11机械效率“有用功、额外功、总功”η=W有/W总×100%效率小于1；机械省力不一定省功12机械能“速度、高度、弹性形变、能量转化”动能+势能；忽略阻力时可守恒匀速下降动能不变，重力势能减小，机械能减小

第一层｜基本模型12题姓名：____________班级：____________日期：____________得分：____________杠杆题：找支点—画作用线—作垂直力臂。1.校车在25s内匀速通过450m，求速度。（3分）________________________________________________________________________________________________________________________________________________________________2.某金属块质量178g，体积20cm³，求密度并判断是否可能是铜（ρ铜≈8.9g/cm³）。（4分）________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________3.一只箱子静止在水平地面上，重120N。写出它受到的两个主要力及其大小关系。（4分）________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________4.用6N水平拉力匀速拉木块。若在木块上增加砝码并仍匀速拉动，测力计示数如何变化？说明依据。（4分）________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________5.一个重300N的人双脚站立时与地面接触总面积为0.04m²，求对地面的压强。（4分）________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________6.同一杯水中A点距水面4cm，B点距水面10cm。比较两点液体压强并说明。（3分）________________________________________________________________________________________________________________________________________________________________7.物体在空气中重5.6N，完全浸没在水中时弹簧测力计示数3.2N，求浮力。（4分）________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________8.水平推力80N使物体前进15m，求推力做功。（3分）________________________________________________________________________________________________________________________________________________________________9.机器在20s内做功1.2×10⁴J，求功率。（3分）________________________________________________________________________________________________________________________________________________________________10.杠杆平衡时，动力为40N，动力臂0.6m，阻力臂0.2m，求阻力。（4分）________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________11.用滑轮组提升重400N物体，物体上升2m，拉力做总功1000J，求机械效率。（5分）________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________12.同一小球从斜面不同高度静止滚下，撞击同一木块。为什么能研究动能与速度的关系？（4分）________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

第二层｜条件变式12题13.运动员前600m用时120s，后400m用时80s，中途停留20s。求全程平均速度。（6分）________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________14.一空心金属球质量270g，外形体积120cm³。若材料密度2.7g/cm³，求空心部分体积。（6分）________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________15.电梯匀速上升时，人受到支持力与重力；电梯加速上升时支持力怎样变化？用运动状态变化解释。（5分）________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________16.同一木块分别平放、侧放在同一粗糙水平面上，用相同速度匀速拉动。滑动摩擦力是否改变？木块对地面的压强是否改变？（6分）________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________17.边长10cm、重20N的正方体，分别以不同面放在水平桌面上。压强是否变化？计算其压强。（5分）________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________18.水和盐水中同一深度处，哪种液体压强大？若U形管高度差不同，应如何得出结论？（5分）________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________19.体积为5×10⁻⁴m³、重4N的物体完全浸没在水中。求浮力并判断松手后的运动趋势。（6分）________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________20.工人提着重100N的箱子水平匀速走10m，再竖直提升1.5m。分别判断支持力在哪一段做功并计算总功。（6分）________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________21.甲、乙两机器做相同的功，甲用时30s，乙用时45s。比较功率；若乙做功更多，能否直接判断功率更大？（5分）________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________22.用撬棒撬石头，若动力臂增大到原来的1.5倍，阻力和阻力臂不变，所需动力变为原来的多少？（5分）________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________23.斜面高1.2m、长5m，把重500N物体匀速推上去，推力150N。求有用功、总功、额外功和效率。（8分）________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________24.跳伞运动员打开降落伞后匀速下降。分析动能、重力势能和机械能的变化，并说明能量去向。（6分）________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

第三层｜综合模型6题25.一辆总质量1.5×10³kg的汽车在平直公路上以72km/h匀速行驶2min，受到的阻力为1.8×10³N。求路程、牵引力做功和功率。（10分）________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________26.底面积0.02m²、高0.3m的柱形容器装有0.2m深的水。求水对容器底的压强；若水重40N，容器底部受到水的压力是否一定等于40N？说明。（9分）________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________27.一个边长0.1m、密度0.6×10³kg/m³的正方体木块漂浮在水面。求木块质量、浮力以及浸入水中的体积。（10分）________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________28.用滑轮组在10s内把重600N物体匀速提升2m，绳端移动6m，拉力250N。求有用功、总功、效率和拉力功率。（10分）________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________29.某同学用天平、量筒和水测不规则小石块密度。请写出实验步骤、记录量、计算式；若先测体积后测质量且石块带水，结果如何偏差？（10分）________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________30.同一辆小车从斜面不同高度下滑，在粗糙程度不同的水平面上运动距离不同。设计实验分别研究“动能与速度”和“阻力对运动”的影响，写出自变量、控制变量和观察量。（12分）________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

30题参考答案与分步得分要点题号参考答案与得分要点