problem of the week for class?

Question

A train, traveling at constant speed, takes 20 seconds from the time it first enters a tunner that is 300 meters long until it completely emerges from the tunnel. one of the stationary ceiling lights in the tunnel is directly above the train for 10 seconds. Find the length of the train.

Answer 1

Well to figure out this problem the first thing you have to do is figure out the velocity of the train... the velocity is v=d/t with the number plugged in that is v=300/20 which turns into v=15m/s now you say the light was above for 10 seconds so we can use the same equation as before v=d/t to find the length (distance of the time) so we are trying to find distance so with some simple algebra we change the equation into d=vt or d=15(10) so the length of the train is 150 m

Answer 2

For the train to completely cover the tunnel , it has to cover a distance of 300 meters + length of train

Let the length of train be x meters

300+ x = 20 seconds

pass a ceiling light = 10 seconds

10 seconds to cover x meters and 10 seconds to cover 300 meters

so length of train = 300 meters ANSWER