Physics Q please help...?

Question

a train is traveling down a straight track at 20m/s when the engineer applies the brakes, resulting in an acceleration of -1.0m/s^2 as long as the train is in motion.

how far does the train move during a 40-s time interval starting at the instant the brakes are applied?

if u guys could also show the work that would be great, thank u guys very much!!

Answer 1

The time it takes to come to a complete stop is found by the following equations;

Velocity=initial velocity+accel*time

The final velocity is 0 meters/second.

0=20 m/s-1m/s*time

Solve for time and you get twenty seconds. The rest of the time the trains is not moving.

Distance is found from the following equation;

breaking distance= initial velocity*t+1/2(a)t^2

breaking distance=20m/s(20)+1/2(-1)(20)^2

breaking distance=200 meters