* Velocity gradient: This refers to the rate of change of velocity with respect to distance. The higher the velocity gradient, the greater the viscous force. Think of it as how quickly the fluid is changing speed across its layers.

* Area of contact: The larger the surface area of the object moving through the fluid, the more fluid it interacts with, and the greater the viscous force.

* Viscosity of the fluid: This is an intrinsic property of the fluid that describes its resistance to flow. The higher the viscosity, the greater the viscous force. Think of honey versus water – honey is more viscous and will create a greater resistance.

We can summarize this in a formula:

F = ηAv/Δx

Where:

* F is the viscous force

* η is the viscosity of the fluid

* A is the area of contact

* v is the velocity of the object

* Δx is the distance over which the velocity changes (related to the velocity gradient)