What is the Velocity of the Balloon When a Man Moves Up a Ladder Attached to It?

[subho123]

Homework Statement

It says that "a man of mass m is standing on a ladder attached to the rope of a balloon of mass M (weight of the ladder and rope can be neglected). The balloon is in a static position. Now the man starts moving upwards through the ladder with a velocity v with respect to the balloon. Now what will be the velocity of the balloon ?"

Homework Equations

Now if the velocity of the balloon and the man with respect to the ground be u and V respectively, then we can say

V - u = v

V = u + v

now if we use the conservation of mementum, then

Mu + m(u + v) = 0

(M+m)u = - mv

u = - mv/(M+m)

Is it right ? This indicates that the balloon will go downwards !

The Attempt at a Solution

Homework Statement

Homework Equations

The Attempt at a Solution

 

[tiny-tim]

hi subho123!

u = - mv/(M+m)

Is it right ? This indicates that the balloon will go downwards !

and why not??

the centre of mass stays in the same place, so if the man goes up, the balloon must go down!

looks fine to me

 

[subho123]

Thanks for ur reply sir...