What is the problem in this article? what solution does the article propose? (site 1)

Porque crees que el agua no podia subir mas de 10 m de altura con ese tipo de bomba

What is the measurement of how fast an object moves relative to a reference point?

Under the action of a constant force an object accelerates at 7.8 m/s2. what will the acceleration be if (a) the force is halved? (b) the object's mass is halved? (c) the force and the object's mass are both halved? (d) the force is halved and the object's mass is doubled?