Does the strength of an electromagnet increase or decrease when you put the current in the opposite direction

Awave is produced in a rope. the wave has a speed of 33 m/s and a frequency of 22 hz.

Aball is thrown horizontally from a cliff at 8m/s .in what direction is the ball moving 2s later?

Astone is thrown with a speed v0 and returns to earth, as the drawing shows. ignore friction and air resistance, and consider the initial and final locations of the stone. which one of the following correctly describes the change δpe in the gravitational potential energy and the change δke in the kinetic energy of the stone as it moves from its initial to its final location? options a.δpe = 0 j and δke = 0 j b.δpe is positive and δke is negative c.δpe = 0 j and δke is positive d.δpe is negative and δke is positive e.δpe = 0 j and δke is negative