The average distance between Earth and the Sun is 1.5 ✕ 10^11 m.

Question

(a)Calculate the average speed of Earth in its orbit (assumed to be circular) in meters per second.
(b)What is this speed in miles per hour?

Answer 1

what is the length of the orbit? (circumference of the circle)

what is the time of the orbital period? (year)
... convert to seconds and divide into the orbit length to find speed

convert m/s to mph ... google will do this conversion

Answer 2

Well, I suppose it does about 2 pi R in 365 days
for m/s:
v = 2 pi R/T = 2 pi *1.5*10^11 m / (365 d*24h/d*3600s/h)
now for part b convert m/s to mi/h