The direct source of energy to move the sailboat is probably wind, since wind is what pushes the sail of the sailboat, which is what propels the sailboat forward. 
Hope this helps!
        
             
        
        
        
Answer:
h - height
Explanation:
gravitational potential energy = m * g * h
m stands for mass. Mass doesn't change in physics
g stands for gravitational acceleration. It is a constant.
h stands for height. When the skater moves up and down the track the height from the ground changes. Therefore this variable does change.
 
        
             
        
        
        
An Organ. Why does the answer need to be 20 characters long?
        
             
        
        
        
Answer:
La ingestión es la introducción de la comida en el aparato digestivo al servicio de la alimentación o de la hidratación, y en la forma que nos es más familiar se realiza a través de la boca. 
Explanation:
El "bocado" o pieza alimentaria que se incorpora debe tener dimensiones mayores a las moléculas para denominarse ingestión.