SOLUTION: A ball is dropped vertically off a 45m building. The function that describes the height of the ball as a function of time is h(t)=-5t^2+45 where height is measured in meters and ti

Question 1088268: A ball is dropped vertically off a 45m building. The function that describes the height of the ball as a function of time is h(t)=-5t^2+45 where height is measured in meters and time in seconds.
A) calculate the height of the ball after 2 seconds [h(2)]
B) calculate the time taken for the ball to hit the ground [h(t)=0]
Answer by addingup(3677) (Show Source): You can put this solution on YOUR website!
A) -5t^2+45 = -5(2)^2+45 = 25 meters
-----------------------
B) The ball has to drop 45 meters (the height of the building).
Gravity: g = 9.8 m/s^2
y: vertical displacement in meters (45 meters)
t = sqrt(2gy)/g
t = sqrt(2gy)/sqrt(g^2) now simplify:
t = sqrt(2y/g)
t = sqrt 2(45)/9.8 = 3.03 seconds

RELATED QUESTIONS
Please help me with this problem too: A ball is thrown horizontally from the top of a... (answered by Boreal)

A ball is dropped vertically from the top of a building 450 meters above the ground. Its... (answered by ikleyn)

A ball is dropped vertically from the top of a building 450 meters above the ground. The... (answered by Alan3354)

If a ball is dropped from the top of a 256-ft building, then the formula h(t)=... (answered by Alan3354)

If a ball is dropped from the top of a 256-ft building, then the formula Expresses... (answered by Alan3354)

If a ball is dropped from the top of a 256-ft building, then the formula h(t)=... (answered by Alan3354)

Good morning, Any help on this one would be greatly appreciated. If a ball is... (answered by KMST)

What is the minimum value of the function y = 3x2 + 2x � 8? and The equation h = 40t �... (answered by stanbon)

A ball dropped from the top of tower A can be modeled by the function h(t) = -9.8t^2 +... (answered by stanbon)