制动衫裂时:Vt=V0+aT1 Vt=0 解得或侍闭 T1=60s S1=V0T1+a1t1^2/2=540m启动时:V=a2T2 T2=30s S2=a2T2^2/谈戚2=270mT=T1+T2+T0=60+30+30=120sS=S1+S2=540+270=810m
物理书看两遍就会了,这个问题…