Question

An arrow is fired vertically up lands 8 seconds later.Find:
[ A] Its maximum height.
[B] Its initial speed.

Answer 1

It takes the arrow 4 seconds to reach the top and 4 seconds to reach the bottom. Solve for height:

d=1/2at^2=1/2(9.8m/s^2)*(4s)^2=78.4m

Initial velocity=time*deceleration=4s*9.8m/s^2=39.2m

Answer 2

Initial velocity=time*deceleration=4s*9.8m/s^2=39.2m/s