a student determines the circumference of a golf ball. a man pulls a sledge of mass 25 kg across level ground with a horizontal force of 60 N. a constant force of friction of 20 N acts on sledge. what is the acceleration of the sledge?

Electric field of the earth. the earth has a net electric charge that causes a field at points near its surface equal to 150 n> c and directed in toward the center of the earth. (a) what magnitude and sign of charge would a 60-kg human have to acquire to overcome his or her weight by the force exerted by the earth’s electric field? (b) what would be the force of repulsion between two people each with the charge calculated in part (a) and separated by a distance of 100 m? is use of the earth’s electric field a feasible means of flight? why or why not?

Aboy with a mass 25 kg climbs into a small tree. he sits on a branch that is 2.o m above to the ground.what is his gravitational potential energy above the ground?

Which form of cell division creates the sperm and egg, resulting in half of the chromosomes as the other cells?