A penny is dropped from a high-rise building that is 350 feet high. After 8.4 seconds the penny hits the ground. Which one of the following quadratic models describe the height of the penny above ground as a function of the time elapsed since the penny was dropped?

Question

Quizplus · Accepted Answer

The height of an object dropped from a height 'h' can be modeled using the equation $h= -16t^2 + vt + h$, where 't' is the time in seconds, 'v' is the initial velocity in feet per second (which is 0 in this case), and 'h' is the initial height in feet. In this case, 'h' is 350 feet. Therefore, the quadratic equation that models the height of the penny above ground as a function of time elapsed since the penny was dropped is:
$$h = -16t^2 + 350$$
After 8.4 seconds, the height of the penny is:
$$h = -16(8.4)^2 + 350 = 0$$
Therefore, the penny hits the ground after 8.4 seconds, which is consistent with the problem statement. The only choice that matches this model is answer choice B.

A Penny Is Dropped from a High-Rise Building That Is