What is the acceleration of the spore during the launch and speed reduction?

[wbetting]

Homework Statement

Catapulting mushrooms. Certain mushrooms launch their spores by a catapult mechanism. As water condenses from the air onto a spore that is attached to the mushroom, a drop grows on one side of the spore and a film grows on the other side. The spore is bent over by the drop's weight, but when the film reaches the drop, the drop's water suddenly spreads into the film and the spore springs upward so rapidly that it is slung off into the air. Typically, the spore reaches a speed of 1.70 m/s in a 5.10 μm launch; its speed is then reduced to zero in 1.00 mm by the air. Using that data and assuming constant accelerations, find the acceleration in terms of g during (a) the launch and (b) the speed reduction.

Homework Equations

vf^2 - vi^2 = 2 a distance
so
a = vf^2 / (2 distance)

The Attempt at a Solution

i got part a correct by doing (1.7^2)/2(5.1x10^-6) then dividing by 9.8 to get 2.9x10^4
so i thought part b for speed reduction could use same formula and velocity (1.7) but different distance now (.001m) so i did (1.7^2)/2(.001m)= 1445 then divided by 9.8 for g unit and got 147.45 and the answer is wrong! I need help!

 

[wbetting]

Just forgot the - sign!