Odpowiedzi

2009-10-28T15:56:47+01:00
l=300m= 0,3km
v= 90km/h
t=t1+t2=37,5s = 37,5/3600 h
x=? Oblicz prędkość statku.

v=s/t -> t=s/v
t₁=l/(v+x)
t₂=l/(v-x)
t=t₁+t₂
t=l/(v+x)+l/(v-x)
t=l*(v-x)/[(v+x)*(v-x)]+l*(v+x)/[(v-x)*(v+x)]
t=l*[(v-x)/(v²-x²)+(v+x)/(v²-x²)]
t=l*[(v-x+v+x)/(v²-x²)]
t/l=2*v/(v²-x²)
(v²-x²)=2*v*l/t
-x²=2*v*l/t-v²
x²=v²-2*v*l/t
x²=90²-2*90*0,3/(37,5/3600)
x²=8100-5184
x²=2916
x=54 km/h
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  • Użytkownik Zadane
2009-10-28T21:01:14+01:00
L=300m= 0,3km

v= 90km/h

t=t1+t2=37,5s = 37,5/3600 h

x=? Oblicz prędkość statku.

v=s/t -> t=s/v

t₁=l/(v+x)

t₂=l/(v-x)

t=t₁+t₂

t=l/(v+x)+l/(v-x)

t=l*(v-x)/[(v+x)*(v-x)]+l*(v+x)/[(v-x)*(v+x)]

t=l*[(v-x)/(v²-x²)+(v+x)/(v²-x²)]

t=l*[(v-x+v+x)/(v²-x²)]

t/l=2*v/(v²-x²)

(v²-x²)=2*v*l/t

-x²=2*v*l/t-v²

x²=v²-2*v*l/t

x²=90²-2*90*0,3/(37,5/3600)

x²=8100-5184

x²=2916

x=54 km/h
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