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.

2 answers

v₀=110 km/h=30.6 m/s
s=v₀t-at²/2,

a=2(v₀t-s)/t²=…
v= v₀-at=…
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?