Average speed=total distance traveled/time. Total distance=the sum of the two short distances=79*2+77*3=389 km. Total time used to travel is 2+3=5 hr. Average speed is 389/5=77.8 km/hr.
Yes, eg., when 2 bodies move in opposite directions
, the relative velocity of each is greater than the individual velocity of either
Explanation:
F = ma, and a = Δv / Δt.
F = m Δv / Δt
Given: m = 60 kg and Δv = -30 m/s.
a) Δt = 5.0 s
F = (60 kg) (-30 m/s) / (5.0 s)
F = -360 N
b) Δt = 0.50 s
F = (60 kg) (-30 m/s) / (0.50 s)
F = -3600 N
c) Δt = 0.05 s
F = (60 kg) (-30 m/s) / (0.05 s)
F = -36000 N