- #1
Frankenstein19
- 56
- 0
Homework Statement
The problem reads: A person throws a ball up in the air with an initial velocity of 15m/2. Calculate the max height reached and how long it is in the air for.
Homework Equations
x = x0 + v0t + 1/2at^2
The Attempt at a Solution
[/B]
I need to calculate the how long the ball is in the air for
My book gives me the answer but only does it in one go
I'd like to divide it into two parts, when it reaches max height, and when it comes down
I keep doing the calculations and I keep getting it wrong
My book does uses y= y0+v0t+ (1/2)*(at^2) to calculate the entire time the ball is in the hair
I would think to use that formula to get the time of the ball until it reaches the max height, like this
11.5=0+15t-4.90t^2
The problem when I do that is that I get a negative value inside of the square root
So I'm stuck there
Then to calculate the time between max height and returning to the thrower's hand, I'd do 0=11.5+15t+4.90t^2 (9.80 is positive here because the object is going in the downward direction, right??) so I would like if someone could tell me what I'm doing wrong
Other people use the other formulas in the book but I don't understand why and I wouldn't think to use them, I would think to use the one I used in the description because when I check what data I know, it lines up with that formula, so please try to use that formula in order to explain because I don't see the logistics in using the other formulasThank you