Answer:
They are moving at a speed of 2/3 meters per second.
Step-by-step explanation:
The field is shown in the attached figure below
As we can see that ant any instant of time Area of the triangle is given by
[tex]A=\frac{1}{2}x\times x\\\\A=\frac{1}{2}x^2[/tex]
Differentiating both sides of the above equation with respect to time we get
[tex]\frac{dA}{dt}=\frac{1}{2}\cdot \frac{dx^2}{dt}\\\\\frac{dA}{dt}=\frac{1}{2}\cdot 2x\cdot \frac{dx}{dt}\\\\\frac{dA}{dt}=x\cdot v[/tex]
Applying values in the given relation we get
[tex]v=\frac{A'}{x}=\frac{2}{3}=\frac{2}{3}m/s[/tex]