To determine the height of a flagpole,Abby throws a ball straight up and times it.She sees that the ball goes by the top of the pole after 0.50 s and then reaches the top of the pole again after a total elapsed time of 4.1 s.How high is the pole above the point where the ball was launched? Neglect air resistance.
A)10 m
B)13 m
C)16 m
D)18 m
E)26 m

Question

Quizplus · Accepted Answer

The ball takes 0.50 s to reach the top of the pole, so it must have an upward velocity of 10 m/s (since it starts from rest). It then takes 4.1 s - 0.50 s = 3.6 s to fall back to the ground, so it must have fallen a distance of 10 m + (1/2) * 9.8 m/s^2 * (3.6 s)^2 = 26 m. Therefore, the pole is 26 m high.

To Determine the Height of a Flagpole,Abby Throws a Ball