Two stars, with masses m1 and m2 that are initially very far apart and at rest (
ID: 2064968 • Letter: T
Question
Two stars, with masses m1 and m2 that are initially very far apart and at rest (and even farther fromany other stars) are pulled together by their gravitational attraction. Find their relative speed when they
are a distance d apart from one another. Put your answer in terms of given quantities (m1, m2, d) and
any relevant physical quantities.
Explanation / Answer
m1*v1 = m2*v2 1/2* (m1*v1^2 + m2*v2^2 ) = G*m1*m2/d => v2 = m1*v1/m2 => v1^2 = 2*G*m2/[ (1 + m1/m2)*d ] => v1 = sqrt( 2G*m2^2/[ (m1+m2)d] ) => v2 = sqrt ( 2G*m1^2/[ (m1+m2)d] ) => the relative velocity is v1 - v2.