Question

Which scenario describes an object experiencing zero net force?
a. a rock falling off a cliff
b. a ballon floating upward at a constant velocity
c. A plane landing on a runway
d. A car driving around a circular race track

Answer 1

The scenario that describes an object experiencing zero net force is:

**b. a balloon floating upward at a constant velocity.**

In this case, the balloon is moving upward at a constant velocity, which means that the forces acting on it (such as buoyancy and gravity) are balanced, resulting in a net force of zero.

In contrast:
- **a. a rock falling off a cliff:** is experiencing a net force due to gravity.
- **c. a plane landing on a runway:** typically experiences forces such as lift, thrust, and drag that are not balanced until it comes to a complete stop.
- **d. a car driving around a circular race track:** is undergoing a centripetal acceleration, which indicates a net force acting toward the center of the circular path.