Answer:
the backpack will be on the ground in 3 seconds but it will first make contact with the ground in 2.5 seconds
Step-by-step explanation:
the equation would be: y = -16t² + 100
if you solve for 't' then you will find the amount of time until it lands
0 = -16t² + 100
-100 = -16t²
100/16 = t²
t = √100/16
t = 10/4 = 2.5
