If a speeding train hits the brake and it takes the train 39 seconds to go from 54.8 m/s to 12 m/s, what is the train acceleration?

1 Answer
Jun 6, 2018

I tried this:

Explanation:

We can use the relationship from Kinematics:

#v_f=v_i+at#

that tells us that the final velocity will depends upon the initial one and the acceleration operating during a certain time.
With your data we get:

#12=54.8+39a#

rearranging:

#a=(12-54.8)/39=-1.097~~-1.1m/s^2#

the negative sign tells us that this acceleration (or de-celeration) will reduce our initial velocity in time.