A tennis ball is dropped from a height of 2.0 m and it rebounds to a height of 1.5 m . If the ball is in contact with the floor for 0.110 s , what is the acceleration of the ball when it is in contact with the floor ?
I am a bit confused with the directions .
For the downward motion , g=-9.81m/s^2 , s=-2.0m and u =0
And when it rebounds which will be the upward motion , g=-9.81m/s^2 . s=1.5
That is what the book says .
For the downward motion , isnt the acceleration due to gravity supposed to be negative since it is in the direction of gravity and the displacement , s , why is it negative ??
And for the upward motion , why is the displacement positive ??