Planets go around the sun in elliptical orbits. The highly exaggerated diagram below shows a portion of such an orbit and the force on the planet at one position along that orbit. The planet is moving to the right.Why choice "b" is the correct answer ?!! enter image description here

  • $\begingroup$ Which answer makes the most intuitive sense to you, and why? $\endgroup$ – Andrew Feb 26 at 12:12
  • 2
    $\begingroup$ To be honest this isn't a very well written question though, I would say b or c could both be reasonable answers given the way the diagram is drawn (I didn't realize at first it was a "top down" view instead of a view at an angle). If they wanted to make it completely unambiguous that b was the answer, they should have included the sun in the diagram, and placed it close to the planet. Maybe this gives you a hint. $\endgroup$ – Andrew Feb 26 at 12:15

A force which is perpendicular to the velocity acts like a centripetal force and does no work. In the (top view) sketch, the force component which is parallel to the orbit acts backward backwards from the velocity and slows it down.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.