In 2004 astronomers reported the discovery of a large Jupiter-sized planet orbiting very close to the star HD 179949 (hence the term 'hot Jupiter'). The orbit was just 1 9 the distance of Mercury from our sun, and it takes the planet only 3.09 days to make one orbit (assumed to be circular). (b) How fast (in km/s) is this planet moving?

Video transcript

Welcome back everybody. We are looking at a giant exoplanet T. O. I. 21 09 B to be specific and it is orbiting around an F. Type star. Now we are told the total time it takes to complete one revolution is 16 hours. And we are told also that the average distance away from its planet during orbit. We're sorry from the star that it is orbiting is 2.67 times 10 to the six km. And we are asked to find how fast the planet is moving. Well when assuming kind of circular motion here, right? We know that the time it takes to complete one revolution is two pi times the distance away from the body. It's revolving around all over its speed, Multiplying by speed on both sides and dividing by the time it takes, we get that our desired speed is just two pi times the distance all over the time it takes to complete one revolution. We know all of these values. So let's just plug those values in. We have that our velocity is two pi times 2.67 times 10 to the six kilometers all over the time it takes to complete one revolution which is 16 hours, but we need this in kilometers per se second. You can see by all our answer choices. So we're going to multiply this by 3600 since there are 3600 seconds in an hour plugging this into our calculator, we get that the planet speed is kilometers per second corresponding to answer choice C. Thank you all so much for watching. Hope this video helped. We will see you all in the next one.