How is force defined in this context?

How is force defined in this context?

• A. The momentum of a moving body
• B. Total pressure acting upon an object
• C. The energy stored in a system
• D. The velocity of a moving object

Answer: (B)

Force in this context is the push or pull that a fluid exerts on a surface. Since pressure is defined as force per unit area, the overall force on an object comes from the total pressure acting over its contact area (in simple cases, F = P × A; more generally, the force is the surface integral of pressure over the area). This means the direction is normal to the surface, and if the pressure varies across the surface, you add up the contributions vectorially. Momentum, energy, and velocity describe motion or stored energy, not how force on a surface is defined.

Force in this context is the push or pull that a fluid exerts on a surface. Since pressure is defined as force per unit area, the overall force on an object comes from the total pressure acting over its contact area (in simple cases, F = P × A; more generally, the force is the surface integral of pressure over the area). This means the direction is normal to the surface, and if the pressure varies across the surface, you add up the contributions vectorially. Momentum, energy, and velocity describe motion or stored energy, not how force on a surface is defined.