·······················1分Р加速路程S2=v2/2a2=225m·····················································2分Р所以总时间T=50+30+60=140s················································Р1分Р又由于如果不停留所需时间t1=(S1+S2)/v=40s···································2分Р所以耽误的时间t=T-t1=100s··················································1分Р29、解:Р(1)由得小灯泡的电阻Р =12Ω·····················································2分Р当闭合S、S1、S2,滑动变阻器滑片位于最右端时,电路中的电流Р =0.25A··························································1分Р电源电压:U=UL+IR==3V+0.25A×36Ω=12V······································2分Р(2)当闭合S、S1,断开S2,滑动变阻器滑片位于最左端时,灯泡正常发光。РR0两端的电压:U0=U-UL=12V-6V=6VР·············································2分Р由得电路中的电流Р =0.5A···························································1分Р由得=12Ω············································2分
全文预览
