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? \bigcirc 5.7 km/h north and 5.8 km/h west are instantaneous speeds, while 8.1 km/h northwest is the average speed. \bigcirc 5.7 km/h north and 5.8 km/h west are average speeds, while 8.1 km/h northwest is the instantaneous speed. \bigcirc 5.7 km/h north and 5.8 km/h west are average velocities, while 8.1 km/h northwest is the instantaneous velocity. \bigcirc 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. First, distinguish between speed and velocity: velocity includes direction, while speed does not. All the given values have directions (north, west, northwest), so they are velocities, not speeds. This eliminates the first two options.
2. Next, distinguish between instantaneous and average velocity: instantaneous velocity is the velocity at a specific moment during motion, while average velocity is the overall displacement from start to finish divided by total time, representing the single velocity that would take you directly from start to end.
3. The values 5.7 km/h north and 5.8 km/h west describe Kiley's velocity during specific segments of her trip (instantaneous for those segments). The 8.1 km/h northwest is the single velocity that describes her overall motion from start to finish, so this is average velocity.

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.