Why is potential energy negative? What does that even mean?

This is really just a definition! When we ask what the potential energy of an object is, we are really asking what energy is available to be extracted. In the case of gravity: two objects separated by an infinite distance are DEFINED to have zero gravitational potential energy. As they fall together their potential energy becomes more negative, and because of the conservation of energy their kinetic energy increases so that the total energy remains zero.

The minus sign in the gravitational potential energy is really just a convention we use to keep track of energy - there is no physical meaning behind it. We could equally define it the other way round so that kinetic energy was negative!

Answered by Ben T. Physics tutor

18327 Views

See similar Physics A Level tutors

Related Physics A Level answers

All answers ▸

If the force between two point charges of charge 'Q1' and 'Q2' which are a distance 'r' apart is 'F' then what would the force be if the charge of 'Q1' is tripled and the distance between them doubled?


A light is shone through a diffraction grating of slit spacing 4.5x10^5 lines per metre. The incident wavelength is 650nm. Find the angle produced by the incident light and the 2nd order maximum.


What is the difference between plastic and elastic collision?


Using Newton's law of universal gravitation, show that T^2 is proportional to r^3 (where T is the orbital period of a planet around a star, and r is the distance between them).


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences