Abby throws a ball straight up and times it. She sees that the ball goes by the top of a flagpole after 0.50 s and reaches the level of the top of the pole after a total elapsed time of 4.10 s. What was the speed of the ball at as it passed the top of the flagpole?
A) 6.40 m/s
B) 16.2 m/s
C) 17.6 m/s
D) 29.0 m/s
E) 33 m/s

Question

Quizplus · Accepted Answer

The ball takes 0.50 s to reach the top of the flagpole and 3.60 s (4.10 s - 0.50 s) to return to the same level. Using the symmetry of projectile motion and the formula v = u + at, where a = -9.8 m/s², the initial speed u can be calculated as 17.6 m/s.

Abby Throws a Ball Straight Up and Times It