Respostas

2014-08-28T08:56:02-03:00
VM=ΔS/ΔT
VM = S-So/T-To
VM = 120-60/7-4
VM = 60/3
VM = 20 m/s

a) 20 m/s

b) 20 x 3,6 = 72 km/h

c) no instante 4s:
 VM = ΔS/ΔT 
VM = 60/4
VM = 15 m/s

no instante 7s:

VM = ΔS/ΔT 
VM = 120/7
VM = 17,14 m/s