# Calculating equatorial velocity

I'm confused about some results I've been getting. I tried calculating the equatorial velocity of Earth by the equation $$R\varpi=v$$, and I got ~465 $$m/s$$. According to various resources, this is correct. But then I tried to calculate it again, using $$g=a_{c}=\frac{v^{2}}{R}$$, and I got ~8000 $$m/s$$.

Obviously, the second is wrong. My question is why? My only guess is that maybe g doesn't work as $$a_{c}$$ in this case due to the normal force from the Earth or something of the sort, but that seems a weak explanation...