E(k)=m(v^2)/2=3 кг*(4м/c)^2/2=(3*16)/2=48/2=24 Дж
P1V1/T1=P2V2/T2
V1=V2
P1/T1=P2/T2
T2=P2T1/P1=16*300/20=240K
<span>Vx/Vy=tg60</span>
<span>Vy=30 </span>
<span>Vx=tg60*30=30sqrt3</span>
На максимальной высоте Ek = Ep
Ek = mV²/2
Ep = mgh
mV²/2 = mgh (сокращаем массу)
V²/2 = gh
h = V²/2g = 100/20 = 5 м
s=s1+s2=0.5s+0.5s<span>
t=t1+t2
t1=0.5s/v1
t2=0.5s/v2
vcp=s/t=s/(t1+t2)=s/(0.5s/v1+0.5s/v2) </span>Сократим на<span> s
vcp=1/(0.5/v1+0.5/v2)=v1*v2/[0.5(v1+v2)]=2*v1*v2/(v1+v2)=2•72•36/(72+36)=5184/108=48 (</span>км/ч<span>)</span>