The net force on an object equals zero when the object is either at rest or moving with a constant velocity (i.e., not accelerating). Based on that principle, the situations where the net force equals zero are:
1. **A car moving at a constant velocity.** (No acceleration, thus net force is zero.)
2. **A ball at rest.** (Not moving, no net force acting.)
3. **A student walking down the hall at a constant velocity.** (No acceleration, thus net