The earth moves around the sun in a nearly circular orbit of ra-dius 1.50 3 1011 m. during the three summer months (an elapsed time of 7.89 3 106 s), the earth moves one-fourth of the distance around the sun. (a) what is the average speed of the earth? (b) what is the magnitude of the average velocity of the earth during this period?

Respuesta :

circumference of orbit = pi*1/2*1.5e11m = 2.356e11 meters
in 13 weeks, there are 13*7*24*60*60 seconds = 7.862e6 seconds
avg speed = 1/4*2.356e11meters/7.862e6sec = 0.07492e5 = 7.49e3m/sec

the avg velocity is 1.414* radius of the orbit