Question

To measure the height of a building without a ruler or tape measure, an engineer drops a rock off the top of the building and finds out it takes 4.9 seconds for the rock to reach the ground. How high is the building
Could you please tell me the steps, as well? I kind of understand how to do it, but some help would be greatly appreciated (:

Thanks.

Answer 1

The relevant equation we can use in this problem is:

h = v0 t + 0.5 g t^2

where h is height, v0 is initial velocity, t is time, g is gravity

 

Since it was stated that the rock was drop, so it was free fall and v0 = 0, therefore:

h = 0 + 0.5 * 9.81 m/s^2 * (4.9 s)^2

h = 117.77 m