Originally Posted By: paul
because I used a minus sign.

a = 67 m/s - 40 m/s / 1 second = 27 m/s/s

put a -40 m/s in there and you get 107 m/s/s


Yes. 107m/s^2 is the acceleration, and is also consistent with the formula you used:

Quote:

a = (sf - si)/t


sf = 67m/s
si = -40m/s
a = (67m/s - -40m/s) / 1s = 107m/s^2