A ball is thrown vertically downward with a velocity of 30 ft from the top of a building.
a.)What it's speed will be after falling 2 seconds
b.)How far it will fall in 2 seconds
c.)What will be its velocity after 30 ft
d.)If the ball was released at 120 ft above the ground, in how many seconds will it strike the ground.
For a I used the equation Vy = Vyo - gt
For b I used the equation ΔY=Vyo(t) - 1/2gt^2
For c I used the equation ΔY=Vyo(t) - 1/2gt^2 in order to find t, or the time it takes to move 30 ft and I got .72 s. Then I put that into the first equation of Vy=Vyo - gt.
For d I used ΔY=Vyo(t) - 1/2gt^2.
The Attempt at a Solution
For a I got -94 ft/s.
For b I got -124 ft/s.
For c I got 53.04 ft/s.
For d I got 2.74 seconds
I have a few questions. First, can someone check if these answers are correct? My professor did not provide an answer sheet for the exam review. Also I was only able to get a proper answer for d if I made the 120 ft negative. If the ball was released at 120 ft above the ground wouldn't it be positive? Also, c gave me some trouble, if it is incorrect, could someone please provide an in-depth explanation? Thank you so much.