Category Archives: Activities

Pi Day Quiz 2019

Edison Tech Center Pi Day Quiz 2019

This year the Edison Tech Center is working on a mapping machine to compete in DARPA’s Subterranean Challenge. This could be used for search and rescue missions, so this year the Pi Day Quiz is all about engineering for rescues.

1) A 100m long rope is wrapped around a perfectly round tree which is 2m away from a 90m deep hole.  Approximately how much rope is wrapped around the tree with a 1m diameter, if four wraps are used?

2) Will the rope from question 1 reach the bottom of the hole?

3) A rope is wrapped around a perfectly round tree. If the amount of friction which holds the rope is (Number of Wraps x (coefficient of friction of rope on tree) x circumference of tree) + (Number of Wraps-1)x(coefficient of friction of rope on rope) x circumference of tree)), what happens if we go from 3 wraps around the tree to 4?

In this example, use these values:
diameter of tree=20 units
coefficient of friction of rope on rope = 0.5
coefficient of friction of rope on tree = 0.3


4) A rope is wrapped around a perfectly round tree. What happens if we find a tree which has a diameter of 24 units instead of 12 units? Use the equation the amount of friction which holds the rope is (Number of Wraps)x(coefficient of friction of rope on tree) x circumference of tree) + (Number of Wraps-1)x(coefficient of friction of rope on rope) x circumference of tree)).

In this example, use these values:
Number of Wraps=3
coefficient of friction of rope on rope = 0.5
coefficient of friction of rope on tree = 0.3

5) Caver Static Rope is designed to minimize rope stretch. As a result, it is stronger when straight than when in a knot. Design a rope hauling system that only uses three knots.

6) Design a rope hauling system using gears to lift ten times the weight that can be lifted with no gears.

7) A rappel rack is a device which winds rope around metal cylinders, known as bars, to create friction to control the speed of rope moving through. Using the equation friction = (coefficient of friction of rope on bar)x(rope on bar contact area), how much more friction would there be if the diameter of the bars were doubled?

8) Design a hauling system which only uses rope, anchors, and pulleys to lift ten times the weight that can be lifted using only rope.

2018 Edison Tech Center Pi Day Quiz

It’s time for the annual Edison Tech Center Pi Day Quiz. Submit your answers by private message on Facebook.

1) An electric quartz crystal clock circuit is
designed. Will the clock maintain the correct
time better if it is a 24 hour clock or a 12 hour

2) The water supply to the Edison Tech Center
starts as a three inch diameter pipe, which is
then connected to a two and one half inch
diameter pipe, which is then connected to a one
inch diameter pipe. Given a constant water
pressure outside the building and ignoring
water friction, what is the speed of the water
inside the different pipes?

3) The Edison Tech Center milling machine
surface can be moved by turning a four inch
diameter handle. One rotation of the handle
moves the machine surface 60/1000 of an inch.

4) An automobile tire decreases in diameter due
to friction on the road. What percentage
odometer error does a 2 mm decrease in
diameter cause on a 381 mm diameter tire?

5) Water friction decreases as pipe diameter
increases. How much water friction is there in
the one inch diameter pipe compared to the
three inch diameter water pipe?

6) An alcohol stove is made out of a cat food can
with a circumference of 20.32 cm. 5 mm holes
are made around the circumference of the can,
spaced 15 mm apart, center to center. How
many holes can be put in the can?

7) A shower has a constant water pressure
supplied. What is the difference in output for a
showerhead with 1 mm holes versus 2 mm

8) Let us model the Mohawk River as a pipe.
When ice builds up on the river, it decreases
the diameter of the pipe. If there is a constant
supply of water in the river, and the ice blocks
half of the diameter of the river, how much does
that change the flow of the river?


Pi Day Quiz 2017

1) Building a wooden window frame, is it stronger to use a circular or an L-shaped bracket over the corner joint?

2) What is the minimum number of nails or screws needed to attach the bracket from Question #1 so that the frame is limited in how it can distort along two axes (X and Y axis)?

3) Does a spherical ice cube last less time, more time, or the same amount of time as a cubic ice cube?

4) Does a cubic ice cube cool the liquid it is submerged in faster, slower, or the same speed as a spherical ice cube?

5) An electrical circuit can be built to reduce frequencies higher than a ‘cutoff frequency’.  What is a formula showing the relationship between the capacitance of the circuit and the ‘cutoff frequency’?

6) An electrical cable is coiled for shipment and when installed still has a 2.5 cm diameter spiral to it.  How does that change the total length of the cable?

Electric City Bike Rescue in September

Last month our resident photog captured moments at the Electric City Bike Rescue. This operation services the public every Thursday at the Edison Tech Center. See our Contact Us page for updated hours.

Every year many tonnes of steel are wasted as it is thrown into landfills across the country. Much of the population has no knowledge of how to fix even minor problems on their bikes, so when they encounter a problem they just throw it away and buy a new one. Not only is this a waste of our planet’s resources, but it is also a shame considering many less fortunate people in our community could use the older bike. The Electric City Bike Rescue helps people understand mechanical basics through applied effort on their bikes.  Here are some photos.

800-IMG_2566 800-IMG_2527800-IMG_2532800-IMG_2548800-IMG_2554800-IMG_2570


Volunteer Opportunities at the Edison Tech Center in Fall-Winter 2016

This fall the Edison Tech Center closed its displays in order to change them out. After a number of years we felt it was a good time to freshen up our public area. The Electric City Bike Rescue program continues each Thursday all throughout the winter.


Behind the scenes help – We are looking for people with a strong interest in technology and engineering who would like to help build the new displays and use their technical or trades background in this effort.

Bicycle Rescue Volunteers – If you would like to help on Thursdays please contact us and let us know you’d like to help with this program.

Submission of engineering papers and curriculum – If you’d like to publish your papers on our website or blog please contact us. We are looking for non-political, non-religious engineering papers which can look at history or current technological events. Many of our online resources have been enriched by experts in the area who added sections to our pages.

Contact Us

Electrical Technology and Mining Gear

After our recent article on the lighting blog about lighting technology for caving I thought I’d check out the Argo Mill museum to see what artifacts they have. Despite the hostile environment of mines the “new” technology of electricity quickly lent itself to the industry of mining in the 1890s.

Oil-wick cap lamp and helmet on display

Oil and kerosene lamps were used by miners prior to the 1890s. These lamps produced heavy fumes and were a problem when tipped. Despite these problems early miners had to deal with this and were always looking for a better light source.

In 1891 Westinghouse built the Ames Power Plant near Telluride to light and power the Gold King Mine. While there were many problems to solve, the effort was generally a success and set an example of how electricity could revolutionize underground operations. Around the same time Thomas Willson sold his patent of the carbide lamp to Union Carbide and the carbide lamp took the world by storm as they were good for everything from bicycles to lighthouses to mining operations. These acetylene gas lamps were great in how they could be tipped at angles as people negotiated narrow passages and they’d still work great.

Different types of carbide lamps, these could be mounted on a helmet or there are hand held version with handles.
Dynamite detonation gear

The Argo Mill has some great artifacts on display of not only lighting technology but early telephone communications gear and dynamite detonation gear. Another way in which electricity revolutionized mining was the development of small powerful electric locomotives to haul carts of ore. These systems replaced the inhumane system of having donkeys drag the tons of rock out. Elihu Thompson and other pioneers of the time worked on cutting edge powerful electric motors to drive these devices. You can see an example of one of these small electric locomotives at the Argo Mill among other interesting artifacts of the 1800s.

Electric Mule and ore carts. These had a pole that connected to power lines located on the tunnel ceiling.
An electric mule motor designed by Elihu Thomson. These were DC motors powered by overhead wires (catenaries). The floor of the mines were often wet so the ceiling was the safest place to put the wires.
Electrical boxes located in the Argo Mill. Powerful electric motors turned belts that rotated machinery used to refine ore to extract the gold, silver, zinc, copper and other metals.
Control for the speed of the electric mule
An early electric headlamp for miners with battery pack.










Glass and ceramic insulators used for telegraph, telephone and utility power in the mines.
Large insulators for supplying AC power to the mill
Steam powered drill used for boring holes into rock, later dynamite would be inserted.
A telegraph key from the 1800s
Early telephones which connected the mine workers miles underground to the surface.
The classic Wheat Lamp used by miners after the 1980s
A durable double bulb incandescent handheld lamp used by miners

We recommend visiting the Argo Gold Mill as there are all kinds of engineering relics of the steam and electrical age. Their website is found at

Also see our article on caving lamp technology history which is related to mining lamp history on our lighting technology blog.

Big Cottonwood Power Company Historic Station

If you find yourself in Utah for skiing or other business and you love Electric Power history like we do, we recommend you take a short trip up to the Stairs Station Hydroelectric Power Plant. While the Salt Lake City area is most famous for Little Cottonwood Canyon, this power plant from 1895 is located a few miles north in Big Cottonwood Canyon. While you cannot get a tour of the facility it is interesting to check out on your way up to the scenic Guardsman Pass.

I was intrigued by the 1895 date which is the same year many great AC hydropower plants were built across the US. The 1895-1896 period represented a time of growth because of a number of factors. The 1880s was a rough time when we didn’t know which standard would prevail: Thomson or Stanley’s single phase AC? Tesla’s two-phase AC? Bradley’s three-phase AC? or would HVDC come out on top above AC?  By 1891 the War of Currents was over when Dobrovolsky demonstrated a complete three-phase AC system in Frankfurt Germany. Over the next few years Charles Steinmetz, Elihu Thomson, Benjamin Lamme, Oliver Shallenberger and many others solved problems and battled or made bids for leading edge patents. The 1893 Redlands Power Plant was a chance for GE to test and develop its three-phase system. Westinghouse was engaged in not the first, but the largest hydroelectric project in history with Niagara Falls. The Stairs Station was built in the same year as Niagara Falls, Folsom and Oregon City Fall’s landmark plants.

The Stairs Station was built by Utah Power to run electric trolleys in Salt Lake City which was only a few miles away. In this way this small station was different from most being built in the West at the time. Most small power stations were built to serve mining operations or mining towns. When the nearby ski areas opened in the 20th century the Stairs Station was used to power the lifts. Eventually as lifts expanded Solitude and other ski areas needed power from multiple sources.

Alta at Night
Alta Ski Area like all ski areas has a high demand for electricity to power lifts and what better way than to use the falling water located in nearby rivers.

Alta ski area was the first ski area in the Salt Lake Area and opened in 1939. Early ski lifts were often crafted from mining tramway systems. The use of suspended cables to transport people and tools up to mining areas were common and you can see pictures of the remains of the original systems on our Smugglers Union Power Plant page at Telluride. Early ski lifts continue to use a combination of grid power or large diesel engines.

The original installation at Stairs included one 2400 volt Westinghouse Generator (three-phase). When the generator windings burned up in 1980 the plant apparatus was renovated to modern standards.

We recommend you read more about Stairs on this nice little article from HYDRO REVIEW. For now here are some photos I took back in January.

300-pipe2  600-1ports

Insulated ports
Original insulated ports in the side of the building


East Side
The eastern side of the powerplant
Stairs Power Station
The sign visible from the road
Water coming down by pipe from the Granite Flume to power the Stairs Station

ETC Educational Activities:
The Stairs Station is on our list of activities to help learn about the world of engineering. We recommend you visit the plant and study the layout, then check out Solitude Ski Area up the valley. See how the lifts run and inquire with the staff about how a given lift runs. You will see how our recreational industry depends on the work of electrical engineers to make it all possible.

Trolley History:
Salt Lake City has a long history of electric trolleys. In the video below you will see our interview with Malcolm Horton on the Brill Bullet trolleys which first were used in Schenectady and then shipped out to Salt Lake for use there.


Below: the modern massive power needs of Salt Lake are quite distant from the first days of the Stairs Station.


Pi Day Quiz 2016

Its time for the annual Edison Tech Center Pi Day Quiz!

2016 Edison Tech Center Pi Day Quiz

1) The Marchant electromechanical calculator consists of several interlocking gears which are driven by an electric motor. If all the gears have a diameter of one unit, and each gear has ten teeth, what’s the total distance the gears travel for the following calculation:

2) The Marchant electromechanical calculator consists of several interlocking gears which are driven by an electric motor. If all the gears have a diameter of one unit, and each gear has ten teeth, what’s the total distance the gears travel for the following calculation:
999 multiplied by 1001

3) In a Synchronous AC motor, the R.P.M.s are ideally equal to (120 X Freq) divided by the number of magnetic poles.
How fast is the outer material of a 1.5” diameter rotor traveling, when energized at 60 Hz on a synchronous, 4 pole motor?
– Question by Shane Pickett, Nidec Drive Systems Engineer

4) The Marchant electromechanical calculator consists of several interlocking gears which are driven by an electric motor. If all the gears have a diameter of one unit, and each gear has ten teeth, what’s the total distance the gears travel for the following calculation:
1001 minus 999

5) A tire company has twenty stacks of tires up to eight tires high, of seven different diameters. What is the most efficient arrangement of the tires to be able to access any tire?
– Question by Gene Bills

6) A machine to weave canvas sacks uses 6 spools of thread evenly placed around a rotating circular spindle. How much more thread is used for a canvas sack with twice the diameter?

7) How much more volume does a canvas sack with twice the diameter of a smaller canvas sack have?