Topic 1.2: Group Questions

Names (group of 3-4): _______________________________________________

Directions: Work through these together as a group — talk it out, don't just divide and conquer. Each of you should be able to explain any answer if called on. These are AP-level questions: most have more than one part, and getting the number right is only part of the credit — showing your reasoning matters just as much.

Question 1 — Calculate

A delivery driver leaves the warehouse and drives 15 km east in 25 minutes to make a drop-off, then drives 9 km west in 15 minutes back toward the warehouse before stopping for a break.

a) Find the driver's average speed for the whole trip so far, in km/h. b) Find the driver's average velocity for the whole trip so far, in km/h. (Define east as positive.)

Work:

Answers: Average speed = ___________ Average velocity = ___________

Question 2 — Justify

Two students argue about Question 1. Student A says, "The average velocity is smaller than the average speed, so the driver must have been going slower than we calculated." Student B disagrees.

Who is correct? Explain using the actual definitions of speed and velocity — don't just say "because the math worked out that way."

Explanation:

Question 3 — Represent

Sketch a simple position-vs-time graph for the delivery driver's trip in Question 1 (warehouse = position 0). Label the two legs of the trip, and mark the point where the driver is farthest from the warehouse.

(Use the space below for your sketch — label your axes.)

Question 4 — Predict a Change

Suppose the driver's return trip (the 9 km west leg) had taken 30 minutes instead of 15 minutes, with everything else the same.

Before recalculating: would the average velocity for the whole trip increase, decrease, or stay the same? Explain your reasoning first, then check it with the math.

Prediction + reasoning (before calculating):

Check (calculate the new average velocity):

Question 5 (stretch) — Acceleration Preview

The driver's speedometer read 0 km/h at the warehouse, climbed to 60 km/h within the first minute of driving, then stayed close to 60 km/h for most of the 25-minute leg to the drop-off.

During which part of the trip was the driver's velocity changing the fastest — the first minute, or the rest of the 25-minute leg? What does that tell you about acceleration during each part? (We'll calculate acceleration values starting in Topic 1.2, Session 4 — for now, just reason about it.)

Reasoning:

Before You Turn This In

Every blank has something written in it — "I don't know" earns you nothing, a reasoned attempt does
Check that your explanations use physics vocabulary (velocity, displacement, direction) — not just "because it's bigger"
Compare your Question 1 answer with the group next to you if there's time

Group points: effort and participation, not just correctness — everyone should be able to explain any answer.