Q3DQ

Question

A helium balloon hovers in mid-air, neither ascending nor descending. Is it in equilibrium? What forces act on it?

Step-by-Step Solution

Verified
Answer

The balloon has zero acceleration which implies that it is in equilibrium. And only two forces act on the balloon; the force of gravity and the buoyant force.

1Step 1: Equilibrium

For an object to be in equilibrium, the net force on the object must be zero. The object in equilibrium can be stationary or moving at a constant velocity.

 

Here, the balloon has zero acceleration, implying it is in equilibrium.

2Step 2: Forces on the helium balloon

Ignoring airflow and the effect of static charges, only two forces act on the balloon; the force of gravity and the buoyant force. As the balloon is stationary in mid-air, that must somehow imply that the balloon’s weight balances the buoyant force.