Question

A smart-phone is thrown upwards from the top of a 480-foot building with an initial velocity of 16 feet per second. The height h of the smart-phone after t seconds is given by the quadratic equation

student submitted image, transcription available belowh = - 16 t 2 + 16 t + 480
When will the smart-phone hit the ground?
t=______seconds

Answer 1

The smart-phone will hit the ground after 4.0 seconds.

Step-by-step explanation:

To determine when the smart-phone will hit the ground, we need to find the value of t when the height h is equal to 0. In the given quadratic equation h = -16t^2 + 16t + 480, set h to 0 and solve for t. This gives us the equation -16t^2 + 16t + 480 = 0. Using the quadratic formula, we find two possible values for t: t = -5.0 seconds and t = 4.0 seconds. Since we are only interested in positive time values, the smart-phone will hit the ground after 4.0 seconds.