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 ▸Why does an α particle cause more ionisation than a β particle if they have the same kinetic energy?
The mercury atoms in a fluorescent tube are excited and then emit photons in the ultraviolet region of the electromagnetic spectrum. Explain (i) how the mercury atoms become excited and (ii) how the excited atoms emit photons.
A ball is thrown at speed u = 10.0 m/s at an angle of 30.0 degrees to the ground at height, s = 0. How far does the ball travel horizontally from its starting position? (Ignore air resistance and taking g = 9.81 m/s^2)
A ball is kicked off a cliff at a height of 20m above ground and an angle of 30 degree from the horizontal, it follows projectile motion and lands after a time t. Its velocity at the maximum height it reaches is 20m/s, how long does it take it to land?