Question

2 zadania
DUŻO PKT !!!!
1.42, 1.43

Answer 1

1.42
dane:
vo = 0
t1 = 6 min = 360 s
v1 = 4 m/s
t = 10 min = 600 s
szukane:
vśr = ?

vśr = s/t
     s = s1 + s2
     s1 = at^2/2
     a = v1/t1
s1 = v1/t1 * t1^2/2 = v1t1/2
s2 = v1(t - t1)
s = v1 * t1/2 + v1(t - t1)
s = 4 * 360/2 + 4(600 - 360) = 720 + 960
s = 1680 m

vśr = 1680m/600s
vśr = 2,8 m/s

1.43
dane:
vo = 72 km/h = 72 *1000m/3600s = 20 m/s
v = 0
a = 0,5 m/s
szukane:
s = ?

s = vot - at^2/2
     a = vo/t
     t = vo/a = 20m/s/0,5m/s2
     t = 40 s
s = 20 * 40 - 0,5 * 40^2/2 = 800 - 400
s = 400 m