# Physics Formulas and Concepts for Pressure, Waves, and Electricity

Classified in Physics

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## Formulas to Calculate Pressure

P=pgh P=F/A Pabs=Pgauge+Patm P=Pa p=kg/m3 g=m/s2 h=m

### Newtons and Pascal

P=Pa Pa=N/m2 Pa in 1 atm 101,325Pa

### Archimedes Principle of Buoyancy

An object submerged in any fluid will experience a buoyant force equal to the weight of the fluid it has displaced.

### Pressure

Air pressure in the wheels of the car, buoyancy: (the force that makes objects float) the boat floats because the fluid is denser than the object.

### Buoyancy

Fw =m*g p=m/v Fb=Fa+Fw

### Waves

Regards to medium mechanical waves (need a medium), electromagnetic (can propagate in a vacuum), regards to propagation longitudinal (parallel to the direction of the propagation), transverse (perpendicular), circular (waves on water, circular fashion).

### Classify Sounds Waves

Lower frequencies infrasonic, highest ultrasonic (20Hz to 20KHz).

### Waves Phenomena

Reflection (the wave reflects on an object), refraction (the wave refracts on a medium and changes the speed; light, diffraction (the wave bends), resonance (when an original wave and the standing wave this occurs when the original wave adds to the reflected wave and creates a wave with a higher amplitude), interference (occurs when 2 different waves arrive at the same place at the same time and they add together, constructive, destructive).

### Sound Measured

We measure loudness of sound waves with a variable called sound pressure level (SPL) measured in decibels (dB). We can hear a sound depending on its frequency.

### Static Electricity

Is produced by friction (rubbing two objects), conduction (passing the electrons to one object to another), induction (force a bunch of electron accumulations).

### Electricity and Metals

Because of the electron sea, that's why metals are highly conductors of electricity.

### Ohm's Law

Voltage is equal to the amount of current by the resistance V=IR V=V I=A R=ohm.

### Kirchhoff's Junction Law

The amount of current entering into the circuit has to be equal to the one leaving. Drop law the rise has to be equal to the drop.

### Power

Watts.

### Parallel

R1*R2/R1+R2.

### Series

R1+R2+R3.

### Types of Lenses

Concave, convex.