Calculating Centripetal Force

[markymark71990]

I am having difficulty with the following question. Could somebody explain why the answer is B? I chose A. Apparently they are plugging in GMM/R^2 instead of MV^2/R for centripetal force and Im not quite sure why

---

Members don't see this ad.

 

[havocgene]

centripetal force in this scenario is equal to gravitational force i believe.

 

[RocketSurgeon]

For any satellite body the centripetal force is the force due to gravity. Remember you need a force to change the direction of an object and the object (satellite) is changing direction to orbit the earth so there has to be a force. There is no other force in the system so the force that is keeping the satellite from flying off into deep space is the gravitational force.

 

[markymark71990]

ok awesome. Thanks for the clarification. Centripetal force always points toward the center of the circle, and in a satellite orbiting a planetary body, gravitational force also points toward the center, right?

 

[medic86]

ok awesome. Thanks for the clarification. Centripetal force always points toward the center of the circle, and in a satellite orbiting a planetary body, gravitational force also points toward the center, right?

In this case, the centripetal force is the gravitational force.

 

[Tappinfool66]

To try and answer your question about why you would use one equation over the other:

In this case, the reason that you wouldn't use the equation F = mv^2/r is because you have two variables that would change (the v and the r) from situation A to situation B. You can use the F = Gm1m2/r^2 equation, though, because that has nothing to do with speed and the only variable is r.

I am having difficulty with the following question. Could somebody explain why the answer is B? I chose A. Apparently they are plugging in GMM/R^2 instead of MV^2/R for centripetal force and Im not quite sure why

 

[TheBoneDoctah]

I am having difficulty with the following question. Could somebody explain why the answer is B? I chose A. Apparently they are plugging in GMM/R^2 instead of MV^2/R for centripetal force and Im not quite sure why

I couldn't figure that out either!

 

[SN2ed]

Thread closed. These types of questions belong in the MCAT Study Q&A forum only.