Carla and Jenny Are Arguing About Whether or Not It

question 2

Multiple Choice

Carla and Jenny are arguing about whether or not it is possible to escape the gravitational field of the Earth. Carla shows Jenny a system where mass m is r_E (not the Earth's radius) distant from Earth and r_P (not planet P's radius) distant from planet P, the mass being on the line connecting the Earth and planet P. Carla states that the mass m has escaped if F_{P on m} = −F_{E on m}. Jenny disagrees. Which one, if either, is correct, and why?

• A) Carla, because the total gravitational force on m is zero at that point.
• B) Carla, because there is no gravitational force from Earth on m at that point.
• C) Carla, because there is no gravitational force on m from Earth when r > r_E.
• D) Jenny, because there is a gravitational force on m from Earth no matter how great the distance from the Earth.
• E) Jenny, because the gravitational force from the Earth can only be blocked by a body that is larger than the Earth.