To solve the problem of finding how long it takes for B to catch up with A again on a circular track, follow these steps:

Step 1: Identify Key Information

• Track length ( L = 100 \, \text{m} ) (implied from the problem context).
• Speed of A: ( v_A = 4 \, \text{m/s} ).
• Speed of B: ( v_B = 6 \, \text{m/s} ).

Step 2: Relative Speed

Since both are moving in the same direction, the relative speed of B with respect to A is:
[ v_{\text{relative}} = v_B - v_A = 6 - 4 = 2 \, \text{m/s} ]

Step 3: Time to Catch Up

For B to catch up with A again, B must cover an extra full lap (100m) relative to A. Time is distance divided by relative speed:
[ t = \frac{\text{Extra distance}}{\text{Relative speed}} = \frac{100}{2} = 50 \, \text{seconds} ]

Answer: 50 seconds. (\boxed{50})

作者声明:本文包含人工智能生成内容。