What is the speed of a point on the equator of the Earth due to Earth's daily rotation? What is the speed of a point at latitude of 45 degrees N? Can I use the radial acceleration equation: a = (V^2) / r or v = (2*pi*r) / period where period = 24 hours = 86400s
Well... since the problem asks for speed, don't you think you should use the formula for speed? (Be sure to use the correct radius.)
Draw yourself a picture. You'll find a right triangle whose hypotenuse is the radius of the earth. One of the sides is the radius you want. Use some trig.