FLU - Introduction to Fluids

Fluids Overview

Introduction

One of the largest ships of all time was a French supertanker called the Batillus. Weighing in at 275,268 tons, it was roughly five times heavier than the iconic Titanic. Now, if you throw a rock into the water it will sink. Yet, this massive engineering marvel easily floats.

If you turn on a water hose, the water leaves the hose at a certain flow rate. If you proceed to partially cover the end of the hose with your thumb, you can get the water to shoot out in a narrow stream at significantly higher speed. The spigot is still allowing the same amount of water to flow into the hose, but you've now changed how quickly it leaves.

These two examples aren't magic. The ship floats and the water speeds up because of basic physics that you will learn about in this unit on fluid dynamics.

Essential Questions

1. How does an object's density relate to its mass and volume?
2. How do you suck liquids up through a straw?
3. How does a hydraulic car lift allow a person to lift a massive car with only a small input force?
4. Why do some objects float in water while others sink?
5. Why does the water from a hose speed up when you cover part of the end of the hose?

Key Terms

1. Archimedes' Principle - states that the upward buoyant force Links to an external site. that is exerted on a body immersed in a fluid is equal to the weight of the fluid that the body displaces.
2. Atmospheric Pressure - the pressure exerted by the weight of the atmosphere, which at sea level has a mean value of 101,325 pascals
3. Buoyancy - is an upward force exerted by a fluid that opposes the weight of a partially or fully immersed object
4. Density - the mass of a substance per unit volume
5. Fluid - a substance (such as a liquid or gas) tending to flow or conform to the outline of its container
6. Gauge Pressure - is the pressure of a system above atmospheric pressure
7. Pascal's Principle - A change in pressure applied to an enclosed fluid is transmitted undiminished to all portions of the fluid and to the walls of its container
8. Phase - different states of matter such as gas, liquid, solid, plasma or Bose–Einstein condensate
9. Pressure - is the force applied perpendicular to the surface of an object per unit area over which that force is distributed
10. Specific Gravity - the ratio of the density of any substance to the density of some other substance taken as standard, usually water

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