Question

kiley went 5.7 km/h north and then went 5.8 km/h west. from start to finish, she went 8.1 km/h northwest. which best describes her numbers? 5.7 km/h north and 5.8 km/h west are instantaneous speeds, while 8.1 km/h northwest is the average speed. 5.7 km/h north and 5.8 km/h west are average speeds, while 8.1 km/h northwest is the instantaneous speed. 5.7 km/h north and 5.8 km/h west are average velocities, while 8.1 km/h northwest is the instantaneous velocity. 5.7 km/h north and 5.8 km/h west are instantaneous velocities, while 8.1 km/h northwest is the average velocity.

Explanation:

1. Velocity vs. Speed: Velocity is a vector (has magnitude and direction), speed is a scalar (magnitude only). The values 5.7 km/h north, 5.8 km/h west, and 8.1 km/h northwest all have direction, so they are velocities, not speeds. Eliminate options with "speed".
2. Instantaneous vs. Average Velocity: Instantaneous velocity is velocity at a specific instant. Average velocity is total displacement over total time. Kiley's motion has two segments (north, then west) – these are likely instantaneous velocities at each segment. The 8.1 km/h northwest is the overall (average) velocity from start to finish (total displacement over total time).
3. Analyzing Options:

• Options with "speed" (first two) are wrong (since directions are given, they are velocities).
• Third option: 8.1 km/h northwest is not instantaneous (it's overall), so wrong.
• Fourth option: 5.7 and 5.8 are instantaneous velocities (at each leg), 8.1 is average velocity (overall displacement), which matches.

Answer:

D. 5.7 km/h north and 5.8 km/h west are instantaneous velocities, while 8.1 km/h northwest is the average velocity.