We were recently having a class on the topic Gravitational Potential. We learned that Gravitational Potential is the "Work done to bring a unit mass from infinite to a point in the gravitational field of an object.". It was mentioned that the work done is against the gravitational field and that is something I didn't understand. A classmate of mine questioned how is the work done against the gravitational field if the motion of the object is towards the field? Which my teacher tried to explain but I didn't understand much. Could you please help me understand?
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This may help. Potential energy curve for intermolecular distance. It is about the electrical potential energy at various distances between two atoms sharing a covalent bond. It explains what potential energy is and how it can be negative. It explains how you can choose the distance where potential energy is $0$. – mmesser314 Oct 10 '21 at 22:51
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A classmate of mine questioned how is the work done against the gravitational field if the motion of the object is towards the field?
Because work can be negative and positive. If it's done in the direction the field 'resists', it's positive (think of lifting an object from the Earth's surface); if it's done in the direction the field 'encourages', it's negative.
The Wikipedia article hints at this as well:
The reference location, where the potential is zero, is by convention infinitely far away from any mass, resulting in a negative potential at any finite distance.
Glorfindel
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