The Short Answer:
Technically, the air from a balloon exerts a contact force when it moves something.
The Explanation:
* Contact Forces: These forces require physical contact between two objects. Think of pushing a box or a bat hitting a ball.
* Non-Contact Forces: These forces act over a distance without direct contact. Examples include gravity, magnetism, and electrostatic forces.
Why Air From a Balloon is a Contact Force:
When a balloon is inflated and released, the air inside it rushes out. This air collides with objects in its path, transferring momentum and causing movement.
* Collision is Contact: The air particles within the balloon *physically contact* the object they are pushing. This contact is what causes the force.
A Deeper Look:
* Pressure: While the air is inside the balloon, it creates pressure on the balloon's surface. This pressure is a result of countless collisions between air molecules and the balloon's surface.
* Pressure and Movement: When the balloon is released, the pressure difference between the inside and outside pushes the air outwards. This air, in turn, pushes against other objects.
Conclusion:
While the air from a balloon might seem to move things without direct contact, it's important to remember that the air itself is composed of particles. These particles collide with the object, making it a contact force.
