Calculate the Increased Speed: Caterpillar's Journey from 3 cm/min to ?

Question

A caterpillar crawls for two minutes at a speed of 3 cm per minute, then increases its speed and continues crawling.

In total, the caterpillar advances 30 cm and its average speed is 4.412 cm per minute.

How fast does it travel after increasing its speed?

Video Solution

Step-by-Step Solution

To solve this problem, we'll proceed as follows:

Let us begin by calculating the distance covered in the initial phase of the journey:

  • Since the caterpillar crawls for 2 minutes at 3 cm per minute, the distance D1 D_1 covered is: D1=3×2=6 D_1 = 3 \times 2 = 6 cm.

Given that the total distance traveled by the caterpillar is 30 cm, the distance covered after increasing its speed, D2 D_2 , is:

  • D2=306=24 D_2 = 30 - 6 = 24 cm.

Next, we use the average speed to determine the total time of the entire journey. The average speed formula is given by:

  • Vˉ=Total distanceTotal time\bar{V} = \frac{\text{Total distance}}{\text{Total time}}
  • Thus, the total time T T is: T=304.4126.8 T = \frac{30}{4.412} \approx 6.8 minutes.

The time taken at the increased speed (t2 t_2 ) is then t2=Tt1=6.82=4.8 t_2 = T - t_1 = 6.8 - 2 = 4.8 minutes.

Finally, to find the increased speed V2 V_2 , we use the relationship:

  • V2=D2t2=244.8=5 V_2 = \frac{D_2}{t_2} = \frac{24}{4.8} = 5 cm per minute.

Therefore, the caterpillar travels at 5 cm per minute after increasing its speed.

Answer

5 5 cm per minute