Final answer:
To calculate the bus's final displacement, we add the distances traveled east and subtract the distance reversed. The bus traveled a total of 18 blocks to the east after combining the three segments of its trip.
Step-by-step explanation:
The student is asked to calculate the bus's final displacement after traveling certain distances in different directions. Displacement is a vector quantity that refers to the change in position of an object, taking into account only the initial and final positions, and not the path taken to get there. To find the displacement, we consider the total distance the bus traveled east and subtract the distance it reversed.
The bus first travels 15 blocks to the east, then reverses for 4 blocks, effectively reducing the eastward distance by 4 blocks, and finally travels an additional 7 blocks to the east. So the total displacement would be calculated by adding 15 blocks and 7 blocks then subtracting 4 blocks, resulting in 18 blocks to the east. Therefore, the bus's final displacement is 18 blocks to the east.
The correct answer to the student's question is:
A. 18 blocks to the east