Posted by Sam on Wednesday, September 3, 2014 at 6:23pm.
my teacher gave me this question for review and i don't know how to do it!! HELP!!!
A ball is thrown upwards, from a building. It's height(h), in meters above the ground seconds(t) after being thrown is given by h(t)=5t^2+15t+50
a) How tall is the building? (explain your answer)
b) How long does it take the ball to reach the ground?
c) For how long is the ball 55m above the ground?

11 Physics  Steve, Wednesday, September 3, 2014 at 7:58pm
surely you have similar question that you can study.
You know that the initial height is the constant term. So, the building is 50m tall
The ball hits the ground when the height is zero. So, just solve for t when h=0
I assume you want to know how long the ball is at least 55m above the ground. It is only at 50m for an instant. So, we want
5t^2+15t+50 >= 55
1/2 (3√5) <= t <= 1/2 (3+√5)
http://www.wolframalpha.com/input/?i=+5t^2%2B15t%2B50+%3E%3D+55
Answer This Question
Related Questions
 Physics  A ball is thrown upwards, from a building. It's height(h), in meters ...
 Physics  A red ball is thrown down with an initial speed of 1.3 m/s from a ...
 physics  A red ball is thrown down with an initial speed of 1.2 m/s from a ...
 college  A blue ball is thrown upward with an initial speed of 19.8 m/s, from ...
 physics  A red ball is thrown down with an initial speed of 1.4 m/s from a ...
 Physics  A blue ball is thrown upward with an initial speed of 19.6 m/s, from a...
 Physics  A red ball is thrown down with an initial speed of 1 m/s from a height...
 physics  A blue ball is thrown upward with an initial speed of 20.6 m/s, from a...
 Algebra  If a ball is thrown vertically upward from a height of 56ft. above ...
 Physics  A red ball is thrown down with an initial speed of 1.2 m/s from a ...
More Related Questions