Question 1

If a sound pulse is sent vertically downward into the sea and its reflected echo from the seafloor returns 6 seconds later, the depth of the water is _______ meters. (The average speed of sound in seawater is 1500m/sec.)

Accepted Answer

The answer of If a sound pulse is sent vertically...

Question 2

A Secchi disk is used to measure the attenuation of

Accepted Answer

A Secchi disk is a circular disk, typically white or black and divided into quadrants, that is lowered into water until it is no longer visible. The depth at which the disk disappears from view, called the Secchi depth, is used to measure the attenuation of light in the water. This measurement is used to determine the transparency or turbidity of the water.

Question 3

Light and sound are _______ by seawater.

Accepted Answer

Seawater can refract, scatter, absorb, and attenuate both light and sound waves. Refraction occurs when waves change direction as they pass into a different density medium, such as from air to seawater. Scattering occurs when waves interact with particles or other obstacles in the water, causing them to change direction. Absorption occurs when the energy of the wave is transferred to the water molecules themselves. Attenuation is a combination of scattering and absorption, where the waves gradually lose energy as they travel through the water due to obstacles and energy transfer to water molecules.

Question 4

Extreme variation in the ocean's temperature is prevented by seawater's

Accepted Answer

Seawater has a high specific heat, meaning that it can absorb and store large amounts of heat energy without its temperature changing significantly. This prevents extreme variations in the ocean's temperature.

Question 5

The pressure increase experienced by equipment lowered to a depth of 1000m is approximately

Accepted Answer

The pressure in the ocean increases by approximately 1 atmosphere (ATM) for every 10 meters (33 feet) of depth. Therefore, at a depth of 1000 meters (3281 feet), the pressure increase would be approximately 100 atmospheres.

Question 6

The maximum penetration of visible light in clear seawater is about ______ meters.

Accepted Answer

The answer of The maximum penetration of visible light in...

Question 7

Which processes cause surface seawater to increase in density?

Accepted Answer

Sea ice formation and surface water evaporation are the processes that cause surface seawater to increase in density. When sea ice forms, salt is left behind in the surrounding water, increasing its salinity and density. Similarly, when surface water evaporates, salt is left behind, increasing the salinity and density of the remaining water.

Question 8

The ______ wavelengths of light penetrate deepest into the ocean.

Accepted Answer

Blue wavelengths of light have the shortest wavelength and thus have the most energy, allowing them to penetrate deepest into the ocean.

Question 9

Fresh water has its maximum density at

Accepted Answer

Fresh water has its maximum density at 4°C because below this temperature, water molecules start to form a structured lattice, thus decreasing the density. Above this temperature, the thermal energy of the water molecules starts to overcome the molecular forces, causing water to expand and its density to decrease as well. Therefore, at 4°C, water has its highest density, making it an important factor in the ecology and physics of aquatic systems.

Question 10

The addition of salt to fresh water to form salt water

Accepted Answer

Adding salt to fresh water increases its density due to the addition of dissolved ions, which adds mass without significantly increasing volume.

Question 11

How many calories must be removed from 5g of pure water at 10 °C to convert the water to ice?

Accepted Answer

To convert 5g of water at 10°C to ice, we need to remove the heat of fusion, which is the amount of energy required to change a substance from a liquid to a solid state without changing its temperature. For water, the heat of fusion is 80 calories per gram. Therefore, to convert 5g of water to ice, we need to remove 5 x 80 = 400 calories. However, since we're starting at 10°C, we also need to remove the heat required to cool the water from 10°C to 0°C, which is the specific heat of water multiplied by the mass and the temperature change, or 5 x 1 x 10 = 50 calories. Therefore, the total calories that need to be removed is 400 + 50 = 450 calories (option C).

Question 12

About how many calories are required to convert 2g of ice at 0 °C to water vapor at 50 °C?

Accepted Answer

To solve this problem, we need to use the formula:

Q = m × ΔH

Where:
Q = energy required (in calories)
m = mass (in grams)
ΔH = enthalpy of transformation

First, we need to calculate the energy required to convert 2g of ice at 0 °C to liquid water at 0 °C:

Q = 2g × 80 cal/g = 160 cal

Then, we need to calculate the energy required to heat the liquid water from 0 °C to 50 °C:

Q = 2g × 1 cal/g°C × 50°C = 100 cal

Finally, we need to calculate the energy required to convert the liquid water at 50 °C to water vapor at 50 °C:

Q = 2g × 540 cal/g = 1080 cal

Adding all these energies together, we get:

Qtotal = 160 cal + 100 cal + 1080 cal = 1340 cal

Therefore, the answer is C: 1340.

Question 13

Changes in water density in the oceans create

Accepted Answer

Changes in water density do indeed create sound shadows, which can affect the propagation of sound waves through the ocean. They also cause light refraction, which is why objects underwater appear distorted when viewed from above. Additionally, changes in water density help to create the SOFAR channel, which is an area of the ocean where seismic waves and other types of sound waves are able to travel extremely long distances without losing much of their energy. Therefore, all of these options are correct.

Question 14

Water heated from below distributes the added heat by _____, whereas the still surface of water heated from above distributes the added heat by ______

Accepted Answer

Water heated from below distributes the added heat by convection, where warmer water rises and cooler water sinks in a cyclical motion. In contrast, the still surface of water heated from above distributes the added heat by diffusion and conduction, where heat is transferred through the water molecules by random molecular motion and contact with neighboring molecules.

Question 15

Which method best transmits heat through water?

Accepted Answer

Convection is the best method for transmitting heat through water as it involves the movement of water molecules from hot regions to cold regions, which helps in spreading the heat evenly throughout the water body. Conduction and radiation are not as effective as convection in water, as water is not a good conductor of heat and radiation requires direct line of sight between the heat source and the receiver.

Question 16

The long red wavelengths of visible light are

Accepted Answer

Long red wavelengths of visible light are absorbed in the first meter of water, which is why water appears blue since blue wavelengths penetrate deeper and are scattered back.

Question 17

Sea surface color observed by satellite instruments is affected by

Accepted Answer

Sea surface color observed by satellite instruments is affected by seawater scattering the light, seawater absorbing solar radiation, and the fluorescence of dissolved compounds. Therefore, all of these options are correct.

Question 18

Density of seawater increases as

Accepted Answer

The density of seawater increases when salinity and pressure increase and temperature decreases. Higher salinity means more dissolved salts, which adds to the mass of the water without significantly increasing its volume, thus increasing its density. Higher pressure compresses the water, making it denser. Lower temperatures decrease the kinetic energy of water molecules, bringing them closer together, which also increases density.

Question 19

Covalent bonds link a water molecule's

Accepted Answer

In a water molecule, the oxygen atom has a partial negative charge due to its higher electronegativity, attracting more electrons towards itself. The hydrogen atoms have partial positive charges. This creates a polar covalent bond between the oxygen and hydrogen atoms, where electrons are shared unequally.

Question 20

Viscosity of ocean water increases primarily

Accepted Answer

Viscosity of ocean water increases as temperature decreases because lower temperatures cause water molecules to move less vigorously, increasing resistance to flow.

Quiz 4: The Physical Properties of Water