Question

(a) What is the gravitational potential energy of a two-particle system with masses 5.4 kg and 3.4 kg, if they are separated by 1.2 m? If you triple the separation between the particles, how much work is done (b) by the gravitational force between the particles and (c) by you?

Answer 1

here,

m1 = 5.4 kg

m2 = 3.4 kg

r1 = 1.2 m

a)

the gravitational potential energy of a two-particle system , PE1 = G * m1 * m2 /r1^2

PE1 = 6.67 * 10^-11 * 5.4 * 3.4 /1.2^2 J = 8.5 * 10^-10 J

b)

r2 = 3 * r1 = 3.6 m

the final gravitational potential energy of a two-particle system , PE2 = G * m1 * m2 /r2^2

PE2 = 6.67 * 10^-11 * 5.4 * 3.4 /3.6^2 J = 0.945 * 10^-10 J

the work done by gravitational potential energy , Wg = PE2 - PE1 = - 7.56 * 10^-10 J

c)

the work done by you , W = 7.56 * 10^-10 J