6. From the top of a 70-meter-high building, a l-kilogram ball is thrown directly downward with an initial speed of 10 meters per second. If the ball reaches the ground with a speed of 30 meters per second, the energy lost to friction is most nearly
(A) 0 J
(B) 100 J
(C) 300 J
(D) 400 J
(E) 700 J
(A) 0 J
(B) 100 J
(C) 300 J
(D) 400 J
(E) 700 J