A track runner starts running at 4 m/s. Twenty five seconds later, the runner has a velocity of 10 m/s. What is the acceleration of the runner? Is this positive or negative acceleration?

Your weave is crusty

By water evaporation from the leaves is created a negative pressure at the top of the tree that promotes the ascension  of the water through channels that are called xylem. there are also two molecule forces that are involved: the intra-water molecules cohesion (water molecules stick to each other) and the adhesion when the water molecules stick to the channels they are running in. this is what enables water to go from the roots to the top of a tall tree.

The answer is one amu.