Freight trains can produce only relatively small acceleration and decelerations.

Question

Freight trains can produce only relatively small acceleration and decelerations.

(a) What is the final velocity (in m/s) of a freight train that accelerates at a rate of 0.0500 m/s2 for 8.00 min, starting with an initial velocity of 4.00 m/s?

__ m/s

(b) If the train can slow down at a rate of 0.650 m/s2, how long (in s) will it take to come to a stop from this velocity?

__ s

(c) How far (in m) will it travel in each case?

__ m (distance traveled during acceleration)

__ m (distance traveled during deceleration)

Explanation / Answer

a) v2-u2=2aS

a=0.05m/s2

t=8min=480seconds

u=4m/s

v(final velocity)=0+0.05*480=24m/s

s=v2/(2a)=242/(2*0.05)=5760m

b) a=0.65m/s2

v=0m/s

u=4m/s

v=0m/s(when train stops)

t=-u/a

t=-4/(-0.65)=6.1538sec

v2-u2=2aS

S=-u2/2a

S=-16/(-1.3)=12.3m

c) therefore, s1=5760m(acce) ,s2(dece)=12.3m

incase of any doubt please comment

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