Why does gravitational potential energy have a negative value?
A point in a gravitational field has an associated gravitational potential. It is defined as the work done required to bring a unit mass from a point an infinite distance to that point in the field. At an infinite distance the potential is zero as it is no longer in the field. Work must be done to move a body from a point in a gravitational field to infinity, where the potential is zero. This implies that the sum of the original energy and the work done is zero and therefore the original potential energy must have been negative.
JP
Related Physics A Level answers
All answers ▸What is the difference between a vector and a scalar quantity?
An infared wave has a wavelength of 1.5 x10^–6 m. The speed of this wave is 2.2 × 10^8 m/s. Calculate the frequency of the wave. Give your answer in standard form and to 2 significant figures.
What is the difference between accuracy and precision?
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).