two particles P and Q of mass 1 kg and 3kg respectively start moving towards each other from rest under mutual attraction what is the velocity of the centre of mass
Answers
Answered by
3
Two particles P and Q of mass 1kg and 3kg Two particles having masses m1 and m2 start moving towards each other from the state of rest from infinite separation. What will be their relative velocity of approach when they are interacting gravitationally at a separation 'r'?
Still have a question? Ask your own!
What is your question?
Ad by ETMONEY
SIP in direct mutual funds with 0% commission.
Start SIP in multiple funds with 1-tap access. Instant KYC. Zero paperwork. Free unlimited transactions.
Get the App
4 ANSWERS

Erik Anson, Physics/Cosmology Ph.D. student
Updated Jan 5, 2018 · Author has 1.5kanswers and 2.7m answer views
Viktor's answer is of course correct, and if you have the time (studying at home, say), it's definitely the way you should do it. Doing out the problem in full like that gives you a more thorough understanding of what's going on, and it's good practice.
That being said, if it's on a timed exam, and all you need is the correct answer, there are easier (and faster) ways to find it, by taking advantage of the fact that it's multiple choice.
Notice that all of the options are in the same form, not completely different; there's no way for two options to both give the same answer, unless that answer is zero.This means that if you can calculate the correct value for any special case, you can identify which of the options is correct.For this particular problem, there is a very simple special case, in which one of the masses is way biggerthan the other one (a pebble and the Sun, say). The huge mass won't move noticeably, and so you have one kinetic energy instead of two, and the entire thing turns into a straight-forward conservation of energy problem, with one equation and one unknown (instead of two of each, as you have in the "full" version).
Alternatively, you can do the
Still have a question? Ask your own!
What is your question?
Ad by ETMONEY
SIP in direct mutual funds with 0% commission.
Start SIP in multiple funds with 1-tap access. Instant KYC. Zero paperwork. Free unlimited transactions.
Get the App
4 ANSWERS

Erik Anson, Physics/Cosmology Ph.D. student
Updated Jan 5, 2018 · Author has 1.5kanswers and 2.7m answer views
Viktor's answer is of course correct, and if you have the time (studying at home, say), it's definitely the way you should do it. Doing out the problem in full like that gives you a more thorough understanding of what's going on, and it's good practice.
That being said, if it's on a timed exam, and all you need is the correct answer, there are easier (and faster) ways to find it, by taking advantage of the fact that it's multiple choice.
Notice that all of the options are in the same form, not completely different; there's no way for two options to both give the same answer, unless that answer is zero.This means that if you can calculate the correct value for any special case, you can identify which of the options is correct.For this particular problem, there is a very simple special case, in which one of the masses is way biggerthan the other one (a pebble and the Sun, say). The huge mass won't move noticeably, and so you have one kinetic energy instead of two, and the entire thing turns into a straight-forward conservation of energy problem, with one equation and one unknown (instead of two of each, as you have in the "full" version).
Alternatively, you can do the
Similar questions