If Zephyr stands on a hilltop and releases a helium-filled balloon, in which direction will the balloon move and why? Respond very briefly.
The helium-filled balloon released by Zephyr will move upward because helium gas is less dense than the surrounding air. This difference in density causes the balloon to experience a buoyant force that pushes it up against the pull of gravity. Additionally, if there is any wind present, the balloon may also drift horizontally in the direction the wind is blowing. However, in the absence of wind, the primary movement of the balloon will be vertical, ascending into the sky due to its buoyancy.