To find the force acting on the object, we use the formula $ F = m \times a $, where $ F $ is the force, $ m $ is the mass, and $ a $ is the acceleration.

The velocity $ v $ is given as $ v = 4 \sqrt{x} $.

Squaring both sides, we have $ v^2 = 16x $.

Differentiate $ v^2 $ with respect to $ x $:

$ 2v \frac{dv}{dx} = 16 $

Solving for $ \frac{dv}{dx} $, we find:

$ \frac{v \, dv}{dx} = \frac{16}{2} = 8 $

The force $ F $ is then calculated as:

$ F = 0.5 \times 8 = 4 \, \text{N} $

Thus, the force acting on the object is 4 N.