15. A block is moving on a horizontal surface. At point A, the block has kinetic energy 60.0 J. During the motion of the block to point B, the forces on the block do a total work equal to -20.0 J. What is the kinetic energy of the block when it reaches point B?
a) 20 J
b) 30 J
c) 40 J
d) 60 J
e) 80 J
f) None of the above answers
16. A small rock with mass 0.100 kg is projected straight upward from the ground. When the rock is 5.0 m above the ground, its speed is 8.0 m/s. What is the maximum height above the ground reached by the rock?
a) 5.8 m
b) 6.7 m
c) 7.6 m
d) 8.3 m
e) 9.9 m
f) None of the above answers