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 no air?
A)20 m
B)30 m
C)50 m
D)70 m

Question

Quizplus · Accepted Answer

We can use the kinematic equation for vertical motion with constant acceleration (due to gravity):

h = vi*t + (1/2)*g*t^2

Where:
h = Height of the building
vi = Initial velocity (upward) = -25 m/s (because the ball is thrown downward)
t = Time taken to hit the ground = 2.0 s
g = Acceleration due to gravity = -9.8 m/s^2 (downward)

Substituting the given values, we get:

h = -25*2 + (1/2)*(-9.8)*(2^2) = 70 m

Therefore, the height of the building is 70 m. The correct answer is D.

A Ball Is Thrown Downward from the Top of a Building