A question about momentum ?

Daniel of mass m1 travels his roller blades with a velocity v1 and joins Mario of mass m2, also on roller blades but who is initally at rest. On joining, they both move together for a distance with a velocity v.





i) write an expression for conservation of momentum in terms of m1,m2, v1 and v.





is this correct : (v1*m1+m2)v ?

A question about momentum ?
Momentum before = Momentum after


(m1*v1) + (m2*0) = (m1+m2)v


(m1*v1) = (m1+m2)v ..........................(1)


I do not know exactly what expression you want, because normally you would have an equation with an = sign in it. I think the following might be what you want:


From equation (1) above


{(m1+m2)v} / (m1*v1) = 1





Or you could write the equation to solve for v, the final velocity


Again from equation (1)


v = m1*v1/ (m1+m2)





Please note: these equations are based on the conservation of momentum law. They do not prove that momentum has been conserved.
Reply:sorry dear, the statement written by u is not correct,


according to conservation principle the equation will be


m1*v1=(m1+m2)v


because initially the second one was at rest so initial momentum=m1*v1


and finally both the bodies get joined and both move with velocity v, so final momentum=(m1+m2)v
Reply:m1v1 + m2v2 = m1v%26#039;1 + m2v%26#039;2





Note that v2 = 0 and v%26#039;1 = v%26#039;2 so





m1v1 = v(m1+m2)





v1 =[ v(m1+m2)]/m1



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