A ball is launched vertically upward from a platform 40m above the ground with speed 20m/s. Take the launch point as origin and upward as positive. Neglect air resistance.
Which pair correctly gives the displacement s (with sign) when the ball hits the ground and the total distance travelled D?
a) s=−40m,D≈60.8m
b) s=+40m,D≈80.8m
c) s=−40m,D≈80.8m
d) s=−40m,D≈40m