A lever is used to lift up a 100N weight. The fulcrum is 10cm from the weight. If the effort force is applied at a distance of 50cm from the fulcrum, what is the effort force required to lift the 100N weight?
A) O N
B) 20 N
C) 50 N
D) 100 N

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