# Physics problem: (speed of a point on earth)

1. ### lmf22

26
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

### Staff: Mentor

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.)

3. ### lmf22

26
How do I figure out the radius at 45 degress latitude?

### Staff: Mentor

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.