A ball is thrown downward from the top of a building with an initial speed of 25 m/s. It strikes the ground after 2.0 s. How high is the building, assuming negligible air resistance?
A) 30 m
B) 70 m
C) 20 m
D) 50 m

Question

Quizplus · Accepted Answer

The height of the building can be found using the equation $y = v_0t + \frac{1}{2}gt^2$, where $y$ is the height, $v_0$ is the initial velocity (25 m/s downward), $t$ is the time (2.0 s), and $g$ is the acceleration due to gravity (approximately 9.8 m/s$^2$ downward). Plugging in the values, we get $y = 25(2) + \frac{1}{2}(9.8)(2)^2 = 50 + 19.6 = 69.6$ m, which rounds to 70 m.

A Ball Is Thrown Downward from the Top of a Building