Final answer:
To support the water strider bug on the surface of the pond, the minimum length of the interface between the water and the bug's legs needs to be determined using the surface tension. The calculation involves dividing the weight of the bug by the surface tension. The same principle applies to calculate the minimum length needed to support a person on the water's surface.
Step-by-step explanation:
In order for the water strider bug to be supported on the surface of the pond by surface tension, the minimum length of the interface between the water and the bug's legs needs to be determined. Assuming the bug weighs 1 × 10-4 N and the surface tension force acts vertically upwards, we can use the equation T = F/L, where T is the surface tension, F is the weight of the bug, and L is the length of the interface. Rearranging the equation to solve for L, we get L = F/T. Substituting the given values, the minimum length of the interface needed to support the bug is 1 × 10-4 N / T.
To calculate the minimum length of the interface needed to support a person weighing 640 N, we can use the same equation. Substituting the new weight into the equation, the minimum length of the interface needed to support the person is 640 N / T.