Which of the following situations represents a negative displacement? (Assume positive position is measured vertically upward along a y-axis.)
A negative displacement occurs when an object moves downward along the y-axis. Therefore, out of the given situations, the one that represents a negative displacement is when an object moves from a higher position to a lower position vertically downward.
In order to determine which situation represents a negative displacement, we first need to understand what displacement means. Displacement is the change in position or the distance between the initial and final positions of an object.
Let's consider the following situations:
1. A person jumps from a rooftop to the ground.
2. An elevator moves upward from the ground floor to the fifth floor.
3. A car moves forward from one traffic light to the next.
4. A ball rolls down a hill.
To determine the sign of the displacement, we need to establish a positive direction on the vertical y-axis. In this case, assuming positive position is measured vertically upward, the positive direction is upward, and the negative direction is downward.
Now, let's analyze each situation:
1. A person jumps from a rooftop to the ground: In this case, the person starts at a higher position (rooftop) and ends at a lower position (ground). Thus, the displacement is negative because it is in the opposite direction of the positive y-axis.
2. An elevator moves upward from the ground floor to the fifth floor: Here, the elevator moves in the positive direction along the y-axis, so the displacement is positive.
3. A car moves forward from one traffic light to the next: Since the car is moving horizontally (along the x-axis) and not vertically, we cannot determine the displacement along the y-axis in this case.
4. A ball rolls down a hill: The ball starts at a higher position and moves downward, opposite to the positive y-axis direction. Therefore, the displacement is negative.
So, the situations that represent a negative displacement are:
1. A person jumping from a rooftop to the ground.
4. A ball rolling down a hill.