Question

A balloon of mass M is floating motionless inthe air. A person of mass less thanMis ona rope ladder hanging from the balloon. Theperson begins to climb the ladder at a uniformspeedvrelative to the ground.How does the balloon move relative to theground?

1.Up with a speed less than v
2.Up with speed v
3.The balloon does not move.
4.Down with a speed less thanvcorrect
5.Down with speedv

Answer 1

The answer is 4th choice. Down with a speed less than v.

Step-by-step explanation:

The momentum of the person and the balloon need to cancel each other out. Momentum formula of the balloon is as following:

`P=M*v`

At the moment of t=0, the person and the balloon has the 0 speed.

When the person starts to climb on a balloon, balloon need to cancel this momentum out. We know that the balloon is more heavier than the person. So balloon need to go down with the speed of less than v.