Question 20

Explanation

Calculating Track Length

It is known that runner A takes $12$ minutes to complete $1$ full lap. Converting this to seconds:

Given that runner A's speed is $v_A = 2$ m/s. The track length ($s_{track}$) can be calculated using the distance formula $s = v \times t$:

Calculating Distance Covered by Runner A and C

Given the running time is $72$ minutes. We calculate how many laps each runner has completed.

For runner A (period $12$ minutes):

For runner C (period $9$ minutes):

Calculating Distance Difference

The difference in distance covered ($\Delta s$) is the difference in the number of laps multiplied by the track length:

Alternative calculation of individual distances:

• Distance A: $6 \times 1.44 = 8.64$ km
• Distance C: $8 \times 1.44 = 11.52$ km
• Difference: $11.52 - 8.64 = 2.88$ km

So, the difference in the length of the track covered by runner A and C is $2.88$ km.