2020年中考物理一輪模擬試卷(江蘇南通卷一)評(píng)分標(biāo)準(zhǔn)

t10J1.5WL123122t10J1.5WL123122江蘇省南通年中考輪模擬測(cè)試物理評(píng)分準(zhǔn)第卷擇題答

B

C

C

A

C

A

B

C

D

C第卷選題11聽到的聲音逐漸減弱能看見指示燈亮金容器S－．、延長(zhǎng)0.、大、＝．(2)0.16將石子和物塊擦干后(5)0.8×10．接電路時(shí)，開關(guān)未斷開、4∶1．活塞、靜止、二力平衡(2)偏小(3)密性(4)C、．

FLV．人和車的總質(zhì)量m90kg+50kg＝，········································(1

分)靜止時(shí)對(duì)水平地面的壓力F＝mg＝＝分)F1400N靜止時(shí)對(duì)水平地面的壓強(qiáng)p＝＝3····················(1分S20×10-2(2)該雪地車以36km/h的度勻速行駛v＝＝10m/s···················(1

分)P根據(jù)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則雪地車發(fā)動(dòng)機(jī)的效率：

×100%＝×100%40%············(1分U2U2(3V)．根據(jù)＝得，燈泡正常工作時(shí)電阻R＝＝＝；····分)P(2)當(dāng)開關(guān)、S閉合斷開時(shí)，燈泡L被路，定值電阻R與動(dòng)阻器并，當(dāng)滑動(dòng)變器R的值最大為Ω時(shí)電路總電流最小，電路總功率最小，1

122212311220.5AI22L22L22I12122212311220.5AI22L22L22I12U4.5V通過的流I＝＝＝0.45A，···········································(1分)1R10ΩU通過滑動(dòng)變阻器的電流：I＝＝＝0.3A，·····························分)15Ω電路最小總功率P＝×（II＝4.5V×）3.375W；分(3)當(dāng)開關(guān)、閉，、斷時(shí)斷，泡L與滑動(dòng)變阻器串，電壓表測(cè)滑動(dòng)變阻器兩電壓。P1.5W燈泡的額定電流I＝＝＝0.5A······································(1分U電路中最大電流為I

＝I＝，R

U＝＝＝Ω·················(1分滑動(dòng)變阻器最小阻值＝RR＝－6Ω＝3；··················(1分因?yàn)殡妷罕砹砍虨椤?V所以在確保電路元件安全情況下動(dòng)變阻器兩端電壓最大為U＝時(shí)，此時(shí)滑動(dòng)變阻器阻值最大，此時(shí)電路中電流：I

U－－3V＝＝＝，·················································(1分R6Ω滑動(dòng)變阻器最大阻值

2

U3V＝＝＝Ω，分)因此滑動(dòng)變阻器的阻值范圍為～Ω。．相等、不同①、=內(nèi)(3)未將木塊②也換成與木塊③相同的木塊(4)適當(dāng)降低小球①下降的高度．(1)(2)右③(4)①和、、②SS、保持滑片位不變③(5)．(1)A增大、橫截積(3)絕緣體、兩個(gè)燈泡的亮度相同燈泡比燈泡亮變暗材鋼做內(nèi)芯、材料鋁做外芯；理由是高壓輸電時(shí)，高壓電線中通過的是交流