Ask a Scientist: Weight at the Equator

By Admin | Published: May 15, 2012

Question:
What would be the difference in my weight (force) between standing at the equator vs standing at one of the poles? I suspect I would weigh less at the equator due to the centrifugal force. Say I weigh 80 kg.

Answer:
At first glance, yes you would weigh a very small amount less at the equator, but one day of over-eating on the airplane to the pole, or of strenuous sweating exercise, will easily mask the predicted weight difference. This answer considers the effect of rotation at the equator, that uses “approximate values” for factors, and ignores the non-spherical nature of the earth and other effects. This simple approach compares

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Ask a Scientist: Tree Line

By Admin | Published: April 24, 2012

Question:

I read an article recently that said certain animal species are moving northward at a measurable rate, a km or so a year if I remember This leads me to ask if the tree line is moving north in Canada or higher up mountains where this exists. And are species changing in the forests?

Answer:

Thank you for your question. Many scientists at the Government of Canada work towards exploring this very question, particularly within the Canadian Forest Service (CFS). A number of studies outside of the CFS have recorded modest shifts northwards in distribution of tree and forest animal species.  The CFS has worked on projecting future shifts based on climate scenarios, as well as examining adaptation options to reduce the impact of climate change on Canada’s forests.

Dan McKenney (Chief, Landscape Analysis and Applications) and his team have created an interactive map which displays current distributions of habitat for plant species (http://planthardiness.gc.ca/), and have been working towards projecting future range limits of tree species across Canada (http://planthardiness.gc.ca/index.pl?m=16&lang=en).

A group of scientists, led by Catherine Ste-Marie (CFS Climate Change Research Coordinator), recently published a special issue on Assisted Migration (Forestry Chronicle, Nov/Dec 2011 – http://pubs.cif-ifc.org/toc/tfc/87/06#d131019e134), examining the possibility of moving tree species north in order to help them adapt to climate change. Although all of the articles address current tree species movement to some degree, Richard Winder’s article on “Ecological implications for assisted migration in Canadian forests” covers the scientific evidence in the most detail.

I hope this has been helpful and please do not hesitate to follow-up on these answers.

-Catherine Ste-Marie, Ph.D.

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Ask a Scientist: Pumping Oil

By Science.gc.ca | Published: April 2, 2012

Question

I am not sure if it is true but I heard that for every barrel of oil that they pump out of the ground they replace it with 3 barrels of water.  Is this true and if so then how does this effect the core of the earth in regards to stability because oil is thicker than water. Would this process also be a reason for the increased activity in volcanoes and earthquakes in the world as it is changing the earth’s original make-up?

Answer

In today’s technology world, all oil or gas extraction requires the use of water to a greater or lesser extent.  For example, in conventional oil extraction, as they are drilling they grind up the rock to make a hole through which the oil and gas will flow out.  This rock material is removed from the hole as they drill by injecting water and mud to push the material out of the ground.  For certain unconventional oil production, they put steam down a drilled hole to heat up the rock and the oil to allow the oil to flow out.  The former is less dependent on water whereas the latter is very water-use dependent and can be as much as 10 barrels of water for each barrel of oil obtained.  Neither process actually uses water to replace the oil in the ground.

The core of the Earth is not affected by oil and gas extraction.  Nor does oil and gas extraction effect volcanic activity or other natural earth processes.

- Ann Therriault

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Ask a Scientist: Fresh Water vs. Salt Water

By Admin | Published: March 22, 2012

Question

At the mouth of a big river like the St. Lawrence, or the Mississippi, where the fresh water meets the salt water of the sea/ocean, is there an area where the ratio of fresh water vs. salt exists where neither a fresh water creature nor a salt water creature cannot exist? And is there a creature that can survive in either pure fresh or pure salt water both?

Answer

Areas where freshwater rivers flow into the ocean are called estuaries, and these do provide challenging environments for many types of aquatic animals. However, they are typically rich in nutrients and may have lots of cover, so they can be very important habitats for fish and invertebrates. This is possible because typically the change from freshwater conditions to full oceanic conditions occurs over a gradient rather than as an abrupt transition from one environment to the other. These gradients of increasingly saline (salty, marine) conditions can extend from a few hundreds of meters in some small estuaries to tens or even hundreds of kilometers in large estuaries such as the St. Lawrence or Mississippi, where waters are slightly fresher (less saline) that full marine conditions quite far out to sea. Moreover, with freshwater lighter than saltwater, there is a gradient with depth as well with the surface waters of an estuary typically less saline than deeper waters in the sample place. The tidal effect also has to be considered as more marine waters move up the estuary and often into the rivermouth as tides rise, and then move out along the estuary as the tides fall. Together these factors mean there are gradual changes in water conditions in essentially all estuaries.
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Ionization Energy of Air

By Admin | Published: March 15, 2012

Question

What’s the laser frequency required to ionize air and what’s the ionization energy of air?

Answer

It is more appropriate to think of air as a mixture of different gases, each one having a different ionization energy. That said, one has to ask oneself which gas they wish to ionize. Let’s look at nitrogen since “air” contains about 78% of it.

Nitrogen has an ionization energy of 1402.3 kJ/mol (amount of energy required to remove 1 mol of electrons from 1 mol of nitrogen gas) or

1402 kJ/mol X 1000 J/kJ / 6.022 X 10^23 = 2.328X10^-18 Joules per atom

Therefore, the wavelength of the laser beam must have at least this much energy to ionize nitrogen. To find the wavelength, we use

E = h*c/lambda

where E is the required ionization energy (in our case 2.328×10^-18), h is Planck’s constant in J*s (http://en.wikipedia.org/wiki/Planck_constant), c is the speed of

light (2.98×10^8 m/s) and lambda is the wavelength of the laser beam.

Plugging in these values and solving for lambda, we get a wavelength of approximately 85nm (far ultra-violet light). Using

f = c / lambda

where f is the frequency, we get a frequency of 3.5×10^15 Hz. It’s a good thing nitrogen requires far ultra-violet light to ionize otherwise sunburns would be far worse!

- Kevin Shortt

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Ask a Scientist: Laser Beam

By Admin | Published: March 6, 2012

Question

What happens to air as a laser beam travels through it?

Answer

This depends on the wavelength of the laser beam.

As this pictureshows: http://fuse.pha.jhu.edu/~wpb/spectroscopy/figures/trans.gif, there are very narrow windows in which laser light can pass (i.e. the atmosphere is transparent and has no effect on the laser light). By contrast, where the atmosphere is “opaque”, all the light is absorbed by the atmosphere. Of course, air is composed of several different gases, each of which respond differently to different wavelengths of laser light. So, depending on the wavelength, the laser will either interact with the gas or it won’t.

For example, one can consider a typical microwave oven and how it works to heat food. Microwaves, as found in a microwave oven (122mm wavelength), interact and are absorbed by water molecules causing them to vibrate more vigorously, resulting in heat, but leave the other food molecules unchanged. By the same token, a laser beam of the appropriate wavelength can interact with one of the gases in air causing the air to heat up (absorption), refract or reflect the light (change the direction in which the light is moving), or even change the wavelength of the light (change of colour of the laser beam).

- Kevin Shortt

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Ask a Scientist: Salt Water Pool

By Admin | Published: February 13, 2012

Question

I have a salt water pool (sodium chloride). These pools are equipped with an electric cell that turns the salt in the pool into chlorine. Since the chlorine evaporates every day, why do I not have to regularly add salt to the water? Is the chlorine produced in this pool the same as the chlorine in a traditional pool?

Answer

As mentioned in your question, the salt added to the pool contains sodium chloride.  The chloride (Cl-), from sodium chloride, is necessary in order for the electric cell to convert or oxidize the chloride to chlorine (Cl2).  The chlorine then reacts with the water so at the appropriate pH it forms a  low concentration of disinfectants called hypochlorous acid (HClO) and hypochlorite (ClO-).   Once these disinfectants are used up with organics, splashed out of the pool, or some of the chlorine dissipates, then more chloride has to be added to the water as the new “chlorine source”.  In regular swimming pools that use tablets, the tablets generate the same disinfectants, hypochlorous acid (HClO) and hypochlorite (ClO-).  By the way, hypochlorite is also the active ingredient in bleach.

- Chadron Friesen

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Ask a Scientist: Nuclear Waste

By Admin | Published: February 2, 2012

Question

Is it possible to use containers made of Cadmium to save the nuclear waste and avoid the risk of Nuclear radiation?

Answer

The concerns are for the more penetrating type of radiation.  If the type of the radiation is x-ray or gamma,  then materials that are dense and have high atomic number are best suited for the job.  The higher the energy of the radiation, the thicker the material has to be in order to shield the radiation.  Rock, soil, and concrete can do the same job, but larger amounts of it will be required.  I suppose cadmium could be used as a barrier to such radiation, but the cost and health risks most likely would out way its benefits.  If the radiation is neutron based than hydrogen-based materials are necessary to absorb the radiation.

- Chadron Friesen

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Ask a Scientist: Hybrid Cars

By Science.gc.ca | Published: December 29, 2011

Video: How many hybrid cars would it take to mitigate global warming?

Ask a Scientist: Hybrid Cars

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Ask a Scientist: Vehicles

By Science.gc.ca | Published: December 2, 2011

Question: My questions are based on the following assumption: The fact that passenger cars share the road with heavy vehicles (transportation of goods) requires standards organizations to adopt stringent safety requirements that are costly in terms of resources. This translates into relatively heavy and complex cars that consume a lot of energy over their life cycles. Assuming it were possible to reorganize the road network to minimize the sharing of the road by heavy vehicles and cars, it would be feasible to allow individuals to use very light (comparable to the weight of a motorcycle) and therefore much more energy-efficient cars. If the necessary changes to standards included a plan to extend the life of these cars, thereby inhibiting planned obsolescence, which consumes more natural resources and energy, it is likely reasonable to assume that the natural life of these cars could be doubled.

Is the potential energy economy quantifiable (on a country-wide scale and for the entire life cycle of the vehicle)? Is this topic already being studied in a Canadian research centre or university? Could these ultra-light vehicles technically be powered by an electricity distribution network running alongside roadways, using the same operating principles as a streetcar system?

Answer: A model could certainly be developed for quantifying energy use (or economy) for such a type of vehicle. Given certain parameters on the weight reductions incurred from these lighter designs, the GHGenius (http://www.ghgenius.ca/) tool developed by NRCan would probably be a good basis for conducting a life cycle analysis. Assuming all personal motor vehicles in Canada were made to follow suit, applying it on a country-wide scale is just a question of modeling an ‘average’ car in GHGenius and then multiplying by the number of cars in Canada (this would give an approximate solution, the accuracy of which would depend on the assumptions made).

Ultra-light vehicles could certainly be powered by an electricity distribution network. The technology for this type of power distribution is well-defined and exists. The better question to ask here is whether this is feasible, economical, and practical. Running lines across every road and highway in Canada would be prohibitively costly to both implement and maintain. It makes sense when the movement of traffic is on a defined path (like a tram line or bus route) but not necessarily as a widespread system for all Canadians. The problem with such a system is that you can only go where there are lines to power the vehicle; the vehicle is dependent on the infrastructure of both the roads and the power source.

The problem is an environmental, economic, and engineering based problem, so there are plenty of places where this research might be taking place. Here are some contacts for further information:

NSERC research chairs that are conducting automotive light-weighting research:

http://www.nserc-crsng.gc.ca/Chairholders-TitulairesDeChaire/Chairholder-Titulaire_eng.asp?pid=394
http://www.nserc-crsng.gc.ca/Chairholders-TitulairesDeChaire/Chairholder-Titulaire_eng.asp?pid=189

University of Waterloo Centre for Automotive Research: http://watcar.uwaterloo.ca/

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