一列火車(chē)以54km/h的速度完全通過(guò)一個(gè)1100m長(zhǎng)的鐵橋,用時(shí)1min20s.求這列火車(chē)的長(zhǎng)度.
v=54km/h=15m/s,t=1min20s=80s;
由v=
得火車(chē)通過(guò)的總路程:
s=vt=15m/s×80s=1200m,
火車(chē)的長(zhǎng)度為L(zhǎng)
車(chē)=s-L
橋=1200m-1100m=100m.
答:這列火車(chē)的長(zhǎng)度為100m.