Final answer:
To model a sum of zero, conditions must result in no net change. Examples include a remote control car that returns to the starting point, a round trip journey with equal displacement in opposite directions, and a ball thrown vertically and caught at the same height.
Step-by-step explanation:
The student's question asks to identify three situations that model a sum of zero. This involves concepts from physics, particularly about motion and forces. When considering a sum of zero, in physics, we often refer to a situation where opposing forces or motions cancel each other out, resulting in no net change in motion or no net force.
Looking at the given options and taking into account the notion of a sum of zero, the correct situations would involve scenarios where there is no net displacement or the combined effects of motions or forces result in no change. For instance, something that returns to its starting point has traveled a distance but has a displacement of zero. Therefore, options that match this description are:
- A remote control car is driven up a ramp and flies into the air to an altitude of 11 inches before returning to the ground. Here, the displacement from the initial position is zero.
- An object that makes a round trip, for example, a car that drives forward 5 kilometers and then back 5 kilometers, ends with a sum of zero displacement.
- A ball thrown into the air that reaches the apex and comes back down would have zero net displacement when caught at the initial height.
These situations all demonstrate conditions where the sum of the motion leads to no overall change in position, hence modeling a sum of zero.