Atrain travels at a velocuty of +50 m/s. it takes 8s to slow down to 5 m/s with constant acceleration. what was it's acceleration

5.635m/s2 is the acceleration of the train

Acceleration = (v - u)/t        u = 50m/s, v = 5m/s, t = 8s

                       = (5 - 50) /8  = -45/8 = -5.625 m/s²

Acceleration = -5.625 m/s², so it actually decelerated by 5.625 m/s² because of the negative sign.

The earths atmosphere is made up of nitrogen and oxygensolids turning into gases is called sublimation.