Chapter 8 - Fluid Mechanics Flashcards
Define absolute motion
Absolute motion is the change of position of a body from one absolute place to another.
Define relative motion
Relative motion is the change of position of an object from one relative place to another.
Define buoyancy
Buoyancy is the tendency of an object to float in a fluid
Define buoyant force
When an object is in water, the water exerts a force on the object called buoyant force. These forces always act vertically. Buoyant force is equal to the weight of the volume of the fluid displaced by the object
Explain how a fluid exerts forces on an object moving through it
Fluids exert forces on objects because of many molecules of the fluid that continuously collide with the surfaces of the object immersed in the fluid
Identify the components of fluid forces
Buoyant force and dynamic force (lift forces and drag forces)
Define drag force
Drag force is a backwards force and comes from two different forces, surface drag, and form drag
Distinguish between surface drag and form drag
Surface drag is also known as skin friction or viscous drag. It is affected by density of the fluid, surface area of object, square of the relative velocity of the object AND roughness of surface and viscosity of the fluid.
Form drag is also known as shape drag or pressure drag. It is affected by density of the fluid, surface area of object, square of the relative velocity of the object AND shape of the object and texture or roughness of the surface.
Define lift force
Lift force is the dynamic fluid force that acts perpendicular to the relative motion of the object with respect to the fluid.
Explain the Magnus effect
A magnus force is a lift force caused by a spin. Slower air on top=high pressure and faster airflow on bottom =low pressure means ball moves right
