# Fluid Mechanics with audio

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Category: Education

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## Presentation Transcript

Fluid Mechanics

### Density :

Measure of compactness What units? Densities of common objects Water 1 g/mL Gold 19.3 g/mL Iron 7.8 g/mL Aluminum 2.7 g/mL Density

### Density :

Intensive property Look at ratio of mass and volume Density

Units? Pressure

### Pressure in a Liquid :

Due to weight of fluid directly above you Both weight of water + weight of atmosphere Does not depend on volume of liquid Same pressure experienced at 1 meter in large body of water vs small body of water Exerted equally in all directions Pressure in a Liquid

### Buoyancy :

Upward force Pressure of water pushing up on submerged object Greatest at bottom due to greater depth Buoyancy

### Volume of water displaced :

A completely submerged object will displace a volume of liquid equal to its own volume Volume of water displaced

### Archimedes’ Principle :

An immersed body is buoyed up by a force equal to the weight of the displaced fluid Archimedes’ Principle

### So how can Iron float? :

Principle of floatation A floating object will displace a weight of fluid equal to its own weight So how can Iron float?

### Boyle’s Law :

If ↑P ↓V assuming T is constant Applies to ideal gases P1V1=P2V2 Boyle’s Law

### Magdeburg Hemispheres :

Magdeburg Hemispheres

### Atmospheric Pressure :

Pressure due to the weight of the atmosphere Density depends on altitude Pressure is not uniform Meteorology—moving fronts and storms Atmospheric Pressure

### Barometer :

Instrument for measuring atmospheric pressure Barometer

### How straws work :

Does not ‘suck’ liquid up Reduce pressure so atmosphere ‘pushes’ liquid up straw How straws work

### Pascal’s Principle :

A change in pressure at any point in an enclosed fluid at rest is transmitted undiminished to all points in the fluid If pressure of water at pumping station is increased by 10 units, then pressure of water in pipes will also increase by units If you change area, you can multiply force Also changes distance, so does NOT violate conservation of energy Pascal’s Principle

Hydraulic Lift

### Buoyancy in a Gas :

An object surrounded by air is buoyed up by a force equal to the weight of the air displaced 1 cubic meter of air is 12 N Objects less dense than air will float Buoyancy in a Gas

### Bernoulli’s Principle :

Includes motion of fluid Where speed of fluid increases, the internal pressure decreases Bernoulli’s Principle

### Roofs flying off buildings :

Roofs flying off buildings