Posted by **Danny** on Friday, June 7, 2013 at 10:57pm.

1. A train traveling at a speed of 110km/h decelerates for 20 seconds. During that time it travels 450 meters.

A) What is the acceleration? = m/s^2

B) What is its speed after deceleration? = km/h

Initial velocity (u) = 110km/h

Time (t) = 20s

Distance = 450m

Using this formula s = ut + 1/2 at^2

I need some help. Thank you.

- Physics -
**Elena**, Saturday, June 8, 2013 at 6:55am
v₀=110 km/h=30.6 m/s

s=v₀t-at²/2,

a=2(v₀t-s)/t²=…

v= v₀-at=…

- Physics -
**Anonymous**, Tuesday, September 16, 2014 at 3:09pm
5. An observer measured an interval of 10s between seeing a lightning flash and hearing the thunder. If the temperature of the air was 20 degrees Celsius, how far away was the source of sound?

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