Question

Calculate the earth's speed in its orbit around the sun in m/s

Answer 1

If you know the radius, R, of the orbit, you can calculate the circumference (approximately, since it is really an ellipse not a circle) as 2*pi*R. This is the distance traveled in one year, or 365.25 days. If you divide the distance by the time, you will get orbital speed. You should adjust the units to whatever your teacher is looking for (miles per hour, or meters per second).