Physics Flashcards
(32 cards)
How much is 1 meter in feet?
3.28 ft
How much is 1 kg in pounds (lbs)?
1.204 lbs
What is the difference between mass and weight?
Mass is the amount of matter in an object measured in kg while weight is the force from gravity on an object (the product between mass and acceleration of gravity 9.81), weight is measured in Newton.
Newton can be given in another unit - which?
kg * m/s^2
How many liters is 1 m^3?
1000 L
How is density calculated?
mass (kg) / volumen (m^3)
What affects the density?
Temperature and pressure.
What is the density of salt- and fresh water?
Salt: 1026 g/L
Fresh: 1000 g/L
How is pressure calculated?
It is the force per area. Force (N) / area (m^2).
100,000 Pa = 1 bar.
Explain atmospheric, hydrostatic and absolute pressure.
Atmospheric: the force of an area exerted on a surface by the weight of air above the area - it is 1 bar
Hydrostatic: caused by the weight of fluid and increase 1 bar per 10 meters.
Absolute: is the sum of atmospheric and hydrostatic pressure (P=D/10+1)
How much does atmospheric pressure decrease per 5000 meters?
50%
What is Archimedes principle in words?
the buoyant force on an object submerged is equal to weight of the liquid displaced by the object. If this buoyant force is greater than the weight of the object the object will float.
Which is more dense seawater or freshwater? And what effect does this have in regards to diving?
Seawater, meaning that divers will be more buoyant and need to carry weights to dive down.
What is the formula of Archimedes principle?
m (kg) = p (kg/l) * V (l)
Why will a diver whose skin is unprotected loose heat even in relatively warm waters?
Because water is an excellent conductor. Conductivity will depend on temperature difference between the warmer and cooler material and the thermal conductivity of the materials.
What happens to light beams as they go from one medium to another e.g. air to water?
It will change velocity which makes it change direction and thereby bend (refraction). Objects will appear larger (30 %) and closer (25%)
How many colours does white light consist of and which one disappear first and last?
7 colours and red will disappear first and blue last.
How does sound act under water?
It moves faster (4.33 times) and you cannot determine the direction.
What is the composition of air?
21 % oxygen, 79 % nitrogen <1 % of mixed gasses (especially argon).
How much CO2 is the maximum that is nontoxic in air composition?
A person should not breathe air containing more than 0.1% CO2 by volume.
What is the problem with carbon monoxide?
It binds to haemoglobin and decrease the amount of oxygen delivered to the body. It is also known as the silent killer.
What is nitrox?
A mixture of oxygen and nitrogen.
What is trimix?
A mixture of oxygen, nitrogen and helium.
What is heliox?
A mixture of helium and oxygen.
