Question

A roofer drops a nail that hits the ground traveling at 26 m/s. How fast was the nail traveling 1 second before it hits the ground?

Answer 1

vf = vi + at 

vf – vi = at

vi= 0, vf=26  and afor nil = 9.8m/s2

26 = 9.8t

t = 26 / 9.8 = 2.65 s
Now we know the total time, so we can calculate the time 1 second before it hit the ground. 

= 2.65 -1 = 1.65s

Now again using the same equation, vf = vi+at, we can find vf
vi = 0, a = 9.8 t=1.65

vf = 0 + 9.8(1.65) = 16.17 m/s
So, the nail is traveling with the speed of 16.17m/s 1 second before it hits the ground.