A student records her motion along a straight east–west hallway during a class break. She starts at a reference point designated as x=0m. The description of her motion is as follows:
• From t=0s to t=4s she walks 8m east at a steady pace.
• From t=4s to t=7s she stops to talk with a friend.
• From t=7s to t=11s she walks 6m west at the same steady pace as before.
Assume east is the +x direction.
Respond to the following prompts in complete sentences and show any supporting reasoning or calculations.
(a) For each of the three time intervals, state the student’s velocity as a signed quantity. Clearly indicate the sign and include appropriate units.
(b) For each interval, state the student’s speed. Explain how speed differs from velocity in both definition and physical meaning for this situation.
(c) During which interval is the magnitude of the student’s velocity greatest? Justify your answer qualitatively rather than by further calculation.
(d) Determine the student’s average velocity and average speed for the entire 11s trip. Interpret the sign of the average velocity in the context of the hallway.