Question

un vagon a inceput sa franeze la viteza v0=20m/s, si s oprit dupa tm =20 s​

Answer 1

v=0

v=v₀+a*tm<=>0=20+20a<=>-20a=20=>a=-1 m/s²

d=v₀*tm+a*tm²/2=20*20-20²/2=400-200=200 m

d'=d/2=200/2=100 m

v'²=v₀²+2*a*d'=20²-2*100=400-200=200=>v'=√200=>v'=14,14 m/s

v'=v₀+a*t'<=>14,14=20-t'=>t'=20-14,14=>t'=5,68 s

t"=tm/2=20/2=10 s

v"=v₀+a*t"=20-10=10 m/s=>v"=10 m/s

v"²=v₀²+2*a*d"<=>10²=20²-2d"<=>100-400=-2d"<=>-300=-2d"=>d"=150 m