- #1
James_22
- 1
- 1
Homework Statement
Homework Equations
y = y0 + Vot + 1/2gt²
The Attempt at a Solution
We have to know when yball = y rock
for the ball : t = t-1 because it's throwed 1 sec later the rock.
we have to fine when yball = yrock :
12.t - 0.5*9.8*t² = 18*(t-1) - 0.5*9.81*(t-1)²..I find the answer with this equation.. t = 1.45 y=7.43
but my first equation was : -12.t - 0.5*9.8*t² = 18*(t-1) - 0.5*9.81*(t-1)²
I put the sign (-) before 12t because I thought when acceleration and velocity have the same direction they have the same sign but when I do that, I don't find the good answer. If someone can explain me that..
Thank you