Odpowiedź:
5.1
s = at^2/2 ==> a = 2s/t^2
a = v/t ==> v = a * t
v = 2s/t^2 * t = 2s/t = 2 * 25/5 = 10m/s = 10 * 3,6 km/h =
36 km/h
5.2
s = v0t + at^2/2
s = at^2/2 (bo v0 = 0)
t^2 = 2s/a
t^2 = 40/2,5
t^2 = 16
t = 4s
Vk = a * t = 2,5 * 4 = 10m/s
Vśr = Vk - V0/2 = 10/2 = 5m/s
5.3
s = at^2/2
a = 2s/t^2 = 360/144 = 2,5 m/s^2
Vk = a * t = 2,5 * 12 = 30m/s = 30 * 3,6 km/h = 108 km/h
5.4
Vk = a * t
t = Vk/a
Vk = 64,8 km/h = 64,8 / 3,6 m/s = 18 m/s
t = 18/0,8 = 22,5s
s = at^2/2
s = 0,8 * 22,5^2/2 = 202,5 m
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