Acceleration Help?

Question

A train is slowing down with an average acceleration of – 5.0 m/s2 (negative sign shows deceleration). If its initial velocity is 50. m/s, how far does it travel in 6.0 seconds?

Answer 1

You will first find the speed at which the train is going at 6seconds, using

Vf = Vi + at

Final velocity = Initial velocity + Acceleration times time

which is

Vf = 50 + -5*6

Vf = 50 - 30

Vf = 20

then find the distance it traveled using

Vf^2 = Vi^2 +2ad

Final Velocity square = initial velocity square + 2 times Acceleration times Distance

which is

20^2 = 50^2 +2*-5*d

400 = 2500 -10d

solve for d and you will get the answer

you should get 210m

Answer 2

D = v(0)T + (1/2)AT^2 where A = -5.0m/s^2 and T=6.0s and v(0)= 50. m/s

D= 300m -(1/2)(5.0)(36.)m = 152.5m