1) At the end of a race a runner decelerates from a velocity of 7.00 m/s at a ra

Question

1) At the end of a race a runner decelerates from a velocity of 7.00 m/s at a rate of 0.500 m/s2. (a) How far does she travel in the next 14.0 s? m (b) What is her final velocity? m/s

2) An express subway train passes through an underground station. It enters at t = 0 with an initial velocity of 19.5 m/s and decelerates at a rate of 0.150 m/s2 as it goes through. The station in 190 m long.

(a) How long is the nose of the train in the station?
s
(b) How fast is it going when the nose leaves the station?
m/s
(c) If the train is 130 m long, at what time t does the end of the train leave the station?
s
(d) What is the velocity of the end of the train as it leaves?
m/s

Explanation / Answer

1 a)v=d/t d=98mts

b)v=u-at=0m/s

2 a)u=d/t t=d/u t=9.74s

b)v=u-at=19.5-0.150*9.74=18.039m/s

c) total distance is 130+190=320m

average velocity =19.1m/s time=320/19.1=16.75s

d)total distance =320m time=16.75s velocity=19.10m/s

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