Q46
2 marksShort AnswerSection E

OR

If average speed of competitor is 5 m/s, then find the average time taken by competitor to put all the potatoes in the bucket.

Arithmetic Progressions
Arithmetic Progressions - Application with Speed-Distance-Time (Potato Race)
Official Answer

Using the total distance 370 m (from the AP sum with a=10,d=6,n=10a = 10, d = 6, n = 10) and average speed 5 m/s, Time = Distance/Speed = 370/5=74370/5 = 74 seconds. So the competitor takes an average of 74 seconds to place all ten potatoes in the bucket.

speed distance timeaverage timepotato racearithmetic progression total distance74 seconds

Marking Scheme

  • 11 mark: correctly identifying total distance = 370 m (from the AP sum) and writing Time = Distance/Speed.
  • 21 mark: correct substitution and final answer of 74 seconds.

Hint

Time = Total distance ÷ Speed = 370÷5370 \div 5.

Quick Oral Answer

Total distance is 370 m and speed is 5 m/s, so time = 370/5=74370/5 = 74 seconds.

Analysis & Explanation

Links the AP result to a simple Speed–Distance–Time application, testing carry-forward accuracy.


Concept

  • Time = Distance ÷ Speed; the distance here is the AP sum (370 m) from the previous part.
  • Combines algebra (AP) with an elementary motion formula — a common interdisciplinary case-study pattern.

Key Points

  • Total distance = 370 m; average speed = 5 m/s.
  • Time = 370÷5370 \div 5 = 74 seconds.

Common Mistakes

  • A wrong total distance carried from the earlier AP step (e.g. using d = 3 instead of 6) propagates an incorrect time here.
  • Method marks are still awarded for correctly writing Time = Distance/Speed even if the carried-forward distance is imperfect, provided working is shown.

Common Mistakes

  1. 1Using an incorrect total distance carried forward from a wrong AP calculation.
  2. 2Confusing speed and time formula, e.g. writing Time = Speed/Distance instead of Distance/Speed.
  3. 3Forgetting units (seconds) in the final answer.

Interesting Facts

An average speed of 5 m/s (18 km/h) is a realistic brisk running pace for a school-level potato race competitor.

This question shows how AP results can feed directly into everyday physics formulas like Speed = Distance/Time, a common cross-topic pairing in CBSE case studies.

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Frequently Asked Questions

Which formula connects speed, distance, and time here?

Time = Distance ÷ Speed. Using the total AP distance of 370 m and speed 5 m/s gives 74 seconds.

Why is this called an 'average' time?

Because the competitor's actual running speed varies throughout the race, but the problem assumes a constant average speed of 5 m/s to simplify the calculation.