You throw a ball downward from a window at a speed of 3.6 m/s. What will the speed of the ball be immediately before hitting the sidewalk 8.3 m below?
Ke at beginning = (1/2)m (3.6)^2
loss in potential = gain in Ke = m (9.8)(8.3)
Ke at end = (1/2) m v^2 = (1/2)m(3.6)^2 + m (9.8)(8.3)
cancel m
multiply by 2
v^2 = 3.6^2 + 2 (9.8)(8.3)
solve for v