PHYSICS · Multi-part · A Level · Physics · Fields and their consequences · Fields and their consequences
Problem
Two point masses are fixed along a straight line. Mass M1=5.0kg is at x=0, and mass M2=20.0kg is at x=0.80m. A small test mass m=0.10kg may be placed anywhere on the line joining the two masses.
Neglect all interactions except those among these three objects.
(a) Derive an algebraic expression for the position x (measured from M1) at which the net gravitational force on the test mass m would be zero.
(b) Using your expression, determine numerically where the test mass must be placed to experience zero net gravitational force. Express your answer as a distance from M1.
(c) Based on your result, state whether the zero-force point lies closer to the 5.0kg mass or the 20.0kg mass, and briefly justify why this is the case.