A train moving at 30km/h accelerates to a speed of 50km/h in 30s. find the average acceleration in m/s² ​

Phase changes are chemical changes. true or false

When the force acting on an object points at least partially in the direction of the motion the work done is considered to be negative

Assume that a person skiing high in the mountains at an altitude of h = 15100 ft takes in the same volume of air with each breath as she does while walking at sea level. determine the ratio of the mass of oxygen inhaled for each breath at this high altitude compared to that at sea level. assume that the air composition (i. e. % of air that is oxygen) is the same at sea level as it is at 15100 ft.