Physics Flashcards
The bending of light as light goes from one medium to another is called what?
The bending of light as light goes from one medium to another is called refraction.
Do objects in water appear closer, or farther away than they really are and by how far?
Objects in water appear closer, due to refraction.
Objects appear 25% closer.
What is the magnification of an object underwater?
The magnification of an object underwater is 33%.
So if you think you see a 4m long shark, it’s really 3m long.
Do objects look 25% closer underwater or 33% closer underwater?
Objects look 25% closer and 33% larger underwater.
What is visual reversal?
Visual reversal is when things appear further away than they really are.
Turbidity is the most important factor affecting visual reversal.
Do objects in cloudy water look further away or closer than they really are?
Objects in cloudy water look further away due to visual reversal.
What is gauge pressure?
Gauge pressure is the pressure of the water without the 1 atmosphere of surface presure.
10 m = 1 atmosphere gauge.
Think about how your guages (computer) depth “guage” reads presure.
What is absolute pressure?
Absolute pressure is 1 atmosphere at sea level + 1 x the hydrostatic pressure of the water column surrounding you.
10 m = 2 atmospheres absolute = 2 ATA.
What does the abbreviation ATA mean?
The abbreviation ATA means Atmospheres Absolute.
What is ambient pressure?
Ambient pressure is the surrounding pressure
= ambient or absolute pressure.
Two of these are the same.
Ambient Pressure; Gauge Pressure; Absolute Pressure.
Which ones?
Two of these are the same.
Ambient = Absolute.
Remember, they both begin with the letter A.
The Greek mathematician Archimedes determined that ‘An object wholly or partially immersed in a fluid is buoyed up by a force equal to the weight of the fluid displaced by the object’.
An object that weighs less than the water it displaces will do what?
An object that weighs less than the water it displaces will float and is positively buoyant.
It’s buoyancy is expressed as a positive number, such as being 2 kgs positive. An object that weighs exactly the same as the water it displaces and neither sinks nor floats is neutrally buoyant.
Because a divers lung volume must remain constant regardless of the depth at which he/she breaths, would the density of the air in the divers lungs change as he/she changes depth?
The density of the air in the divers lungs won’t change at depth.
When we breathe, we must breathe a “full” breath regardless of the pressure surrounding us. And, to be able to breathe, the external pressure must be equal to the air we are breathing.
The effect is caused by the difference between the surface air pressure and the water pressure surrounding your chest.
Which law dictates this?
“If the pressure increases (gets more), the more gas will be dissolved (go into) the liquid (on gassing) and If pressure (depth) decreases on a liquid, dissolved gases come out of solution (off gassing)”.
Henry’s Law dictates that,
“If the pressure increases (gets more), the more gas will be dissolved (go into) the liquid (on gassing) and If pressure (depth) decreases on a liquid, dissolved gases come out of solution (off gassing)”.
Which law deals with the relationship between pressure and volume?
It states that for a fixed quantity of gas (at constant temperature) and the volume of the gas is inversely proportional to the pressure of the gas.
Boyles Law deals with the relationship between pressure and volume.
It states that for a fixed quantity of gas (at constant temperature) and the volume of the gas is inversely proportional to the pressure of the gas.
Which law says that at 10metres the pressure is 2 ATA?
Boyle’s Law says that at 10metres the pressure is 2 ATA.
What is gas tension?
Gas tension is the pressure exerted by gasses dissolved in a liquid.
The more gas that is dissolved in a liquid, the greater the gas tension.
What is supersaturation?
Supersaturation is when gas is dissolved in a liquid at equilibrium, then surface pressure is reduced, (ascent) gas tension becomes higher than the surface tension, and the gas comes out of solution.
What is conduction?
Conduction is the transmission of heat by direct contact.
What is the transmission of heat energy by fluids called?
The transmission of heat energy by fluids called convection.