- #1
Rob K
- 33
- 0
Homework Statement
A baseball is thrown downward from a 12.5m tower with and initial speed of 4.5m/s. Determine the speed at which it hits the ground and the time of travel.
s = 12.5m
u = 4.5m/s
a = g = 10m/s^2
Homework Equations
Motion equations used
s = ut + 0.5at^2
v^2 = u^2 +2as
Quadratic equation
x = (-b +/- sqrt( b^2 - 4ac))/2a
The Attempt at a Solution
This is what I started with, and rearranged to put into the quadratic formula.
12.5 = 4.5t + 0.5(10)t^2
therefore:
5t^2 + 4.5t - 12.5 = 0
Where:
a = 5
b = 4.5
c = 12.5
The answer I get is 1.194 seconds
The answer in the book says exactly half that at 0.597 seconds.
Then for part two:
v^2 = u^2 + 2as
seemed the right one.
and I consistently get 16.439m/s
yet the answer in the book says 23.9m/s
I would be grateful for any input on this.
Kind Regards
Rob K