2020年中考物理一轮模拟试卷(江苏南通卷一)评分标准

t10J1.5WL123122t10J1.5WL123122江苏省南通年中考轮模拟测试物理评分准第卷择题答

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C第卷选题11听到的声音逐渐减弱能看见指示灯亮金容器S－．、延长0.、大、＝．(2)0.16将石子和物块擦干后(5)0.8×10．接电路时，开关未断开、4∶1．活塞、静止、二力平衡(2)偏小(3)密性(4)C、．

FLV．人和车的总质量m90kg+50kg＝，········································(1

分)静止时对水平地面的压力F＝mg＝＝分)F1400N静止时对水平地面的压强p＝＝3····················(1分S20×10-2(2)该雪地车以36km/h的度匀速行驶v＝＝10m/s···················(1

分)P根据P＝可得，所受阻力f＝＝＝＝800N···················(1分v10m/sWPt＝8×103

W×2×3600s＝5.76×10

J·············································(1分)Q＝mq3.6kg×4×10＝1.44×10J············································(1)

J则雪地车发动机的效率：

×100%＝×100%40%············(1分U2U2(3V)．根据＝得，灯泡正常工作时电阻R＝＝＝；····分)P(2)当开关、S闭合断开时，灯泡L被路，定值电阻R与动阻器并，当滑动变器R的值最大为Ω时电路总电流最小，电路总功率最小，1

122212311220.5AI22L22L22I12122212311220.5AI22L22L22I12U4.5V通过的流I＝＝＝0.45A，···········································(1分)1R10ΩU通过滑动变阻器的电流：I＝＝＝0.3A，·····························分)15Ω电路最小总功率P＝×（II＝4.5V×）3.375W；分(3)当开关、闭，、断时断，泡L与滑动变阻器串，电压表测滑动变阻器两电压。P1.5W灯泡的额定电流I＝＝＝0.5A······································(1分U电路中最大电流为I

＝I＝，R

U＝＝＝Ω·················(1分滑动变阻器最小阻值＝RR＝－6Ω＝3；··················(1分因为电压表量程为～3V所以在确保电路元件安全情况下动变阻器两端电压最大为U＝时，此时滑动变阻器阻值最大，此时电路中电流：I

U－－3V＝＝＝，·················································(1分R6Ω滑动变阻器最大阻值

2

U3V＝＝＝Ω，分)因此滑动变阻器的阻值范围为～Ω。．相等、不同①、=内(3)未将木块②也换成与木块③相同的木块(4)适当降低小球①下降的高度．(1)(2)右③(4)①和、、②SS、保持滑片位不变③(5)．(1)A增大、横截积(3)绝缘体、两个灯泡的亮度相同灯泡比灯泡亮变暗材钢做内芯、材料铝做外芯；理由是高压输电时，高压电线中通过的是交流