S1=v1t1
=20m/s*20s
=400m
S2=v2t2
=40m/s*60s
=2400m
S =S1+S2
=400m+2400m
=2800m
t =t1+t2
=20s+60s
=80s
v =S/t
=2800m/80s
=35m/s
楼上大意喽!
S1=v1t1
=20m/s*20s
=400m
S2=v2t2
=40m/s*60s
=2400m
S =S1+S2
=400m+2400m
=2800m
t =t1+t2
=20s+60s
=80s
v =S/t
=2800m/80s
=35m/s
楼上大意喽!