Author: The Editor

Work-Energy Theorem

  1. Take your Smart Cart out of the box.

  2. Turn it on and open your choice of software: SPARKvue or Capstone.

  3. Wirelessly connect to the Smart Cart.

  4. Change the sample rate of the Smart Cart Position and Force sensors to 40 Hz.

  5. Make a graph of Force vs. Position and another graph of Velocity vs. Time.

  6. Install the hook on the Smart Cart’s force sensor. Without anything touching the force sensor, zero the force sensor in the software.

  7. Put a rubber band on the force sensor hook. Start recording and while one person holds the rubber band in place, the other person slowly pulls the cart back, stretching the rubber band. Then hold the cart in place with the rubber band stretched and stop recording. Do not let go of the cart or rubber band.

  8. Start recording again. Let go of the cart and move the hand holding the rubber band out of the way. Let the cart go up to its maximum speed and then stop recording.

Analysis

  1. Determine the work done in stretching the rubber band by finding the area under the Force vs. Position curve.

  2. Determine the work done as the stretched rubber band pulls the cart by finding the area under the Force vs. Position curve.

  3. On the Velocity vs. Time graph, determine the maximum velocity. Calculate the kinetic energy of the cart and compare to the work done to accelerate the cart.

  4. Why isn’t the work done to stretch the rubber band equal to the work done to accelerate the cart?

Sample Data

The work done loading the rubber band is -1.91 Nm. The work done unloading (when the cart is launched) the rubber band is 0.77 Nm. The resulting kinetic energy of the cart is

KE = ½ mv2 = ½ (0.252 kg)(2.34 m/s)2 = 0.69 J. This is 10% less than the energy available in the stretched rubber band.

The energy stored in the rubber band is less than the work done to stretch the rubber band. Some of that energy goes into heating the rubber band and making the rubber band move.

Static and Kinetic Friction

 

  1. Take your Smart Cart out of the box.

  2. Turn it on and open your choice of software: SPARKvue or Capstone.

  3. Wirelessly connect to the Smart Cart.

  4. Make a graph of Force vs. Position.

  5. Make sure the Smart Cart Force sensor (with the magnetic bumper on it) is not touching anything and then zero the Force sensor in the software.

  6. Set the cart bumper against the book. Start recording. Very slowly push the cart until the book breaks loose and then push it steadily across the table. Stop recording.

  7. Take another run, pushing it at a faster speed once it breaks loose.

  8. Add a second book on top of the first book and repeat.

Analysis

  1. For each run, record the maximum force before the book moved. This is an indication of the static friction. If you can find the mass of the book, you can calculate the static coefficient of friction for the book on the table.

  2. For each run, record the average force while the book was moving. This is an indication of the kinetic friction. If you can find the mass of the book, you can calculate the kinetic coefficient of friction for the book on the table.

  3. What effect does speed have on the kinetic friction?

  4. What changes when the extra book is added? Do the coefficients of static and kinetic friction change?

Sample Data

The average kinetic friction for two books is 6.92 N.

The average kinetic friction for one book going slower vs. faster was 3.35 N compared to 4.19 N. This indicates that the speed does influence the kinetic friction slightly.

Mass of First Book = 1.56 kg

Mass of Second Book = 1.58 kg

For one book:

μs = F/mg = 3.09N/(1.56)(9.8) = 0.2

μk = F/mg = 3.17N/(1.56)(9.8) = 0.2

For two books:

μs = F/mg = 7.11 N/(1.56+1.58)(9.8) = 0.2

μk = F/mg = 6.59N/(1.56+1.58)(9.8) = 0.2

Hooke’s Law

Hooke’s Law states:
where F is the force of the spring, k is the spring constant, and x is the distance the spring has been stretched.

  1. Take your Smart Cart out of the box.

  2. Turn it on and open your choice of software: SPARKvue or Capstone.

  3. Wirelessly connect to the Smart Cart.

  4. Make a graph of Force vs. Position.

  5. Install the hook on the Smart Cart Force Sensor. Make sure the Smart Cart Force sensor is not touching anything and then zero the Force sensor in the software.

  6. Put one end of a spring on the hook and hold the other end stationary with your hand. Move the cart slightly to put a little tension on the spring.

     

  7. Start recording and pull the Smart Cart away from the fixed end of the spring until the spring is stretched out. Then stop recording.

Analysis

  1. On the Force vs. Position graph, apply a linear fit to the straight-line part of the graph.

  2. Determine the spring constant from the slope of the linear fit.

Sample Data


The slope of the graph indicates the spring constant is 6.77 N/m.

Impulse Demonstration

Equipment:

Smart Cart

Accessory Rubber Bumper

Learning Outcome:

A force acting on an object for a period of time imparts an impulse to that object which is defined as a change in momentum.

Experimental Setup:

  1. Take your Smart Cart out of the box

  2. Attach the rubber bumper accessory (included with Smart Cart) to the force sensor on the Smart Cart.

  3. Press the power button on the side of the Smart Cart to turn it on.

  4. In SPARKvue or Capstone, pair the Smart Cart to your computer or device. Here are a couple short videos to help you pair in either software:

    1. SPARKvue: https://www.youtube.com/watch?v=tsdHWu4quNo

    2. Capstone: https://www.youtube.com/watch?v=JGy-UG245lY

  5. In the software, you will need to create a graph of Force vs. Acceleration.

    1. In SPARKvue:

      1. Under “Quick Start Experiments” choose: Impulse

      2. Increase the sampling rate of the Force sensor to 1KHz

    2. In Capstone:

      1. Create two graph displays

      2. Graph 1: [Force] vs. Time

      3. Graph 2: [Velocity] vs. Time

      4. Increase the sampling rate of the Force sensor to 1KHz

You will push the cart into a barrier such that the rubber bumper will collide and bounce the cart off the barrier. A wall, book or other solid vertical surface will work.

Data Collection:

  1. Zero the force sensor

  2. Press the record data button

  3. With the rubber bumper facing towards the barrier, give the Smart Cart a push.

  4. After the Smart Cart has reversed direction, stop data collection.

 

Data Analysis:

  1. On the Force vs. Time graph, use the Area tool to measure the area under the curve. This is the impulse that the Smart Cart experienced.

  2. On the Velocity vs. Time graph, use the Coordinate tool to find the velocity just before the impact of the Smart Cart against the barrier and record this value. This is the Smart Cart’s initial velocity.

  3. Next, using the Coordinate tool find the velocity after the collision with the barrier. Record this value. This is the Smart Cart’s final velocity.

  4. Weigh the cart without any bumper and record the mass. You may also estimate the mass of the Smart Cart to be around 0.250 kg.

Calculate the change in momentum of the Smart Cart: pf – pi

Compare your calculated value to the area under the Force vs. Time graph.

Sample Data:

This data was created with a Smart Cart that measured 0.246 kg, for an error around 1.5%.

Centripetal Acceleration and Force

  1. Take your Smart Cart out of the box.

  2. Turn it on and open your choice of software: SPARKvue or Capstone.

  3. Wirelessly connect to the Smart Cart.

  4. Make a graph of Acceleration-x (from the Smart Cart Acceleration Sensor) vs. Angular Velocity-y (from the Smart Cart Gyro Sensor). Add a second plot area with the Force vs. Angular Velocity-y.

  5. Install the rubber bumper on the Smart Cart Force Sensor. With the cart sitting still, with nothing touching the rubber bumper on the Force Sensor, zero the Acceleration-x, Angular Velocity-y, and the Force in the software.

  6. Set up a board or track on a rotatable chair as shown in the picture. Set the end stop near the end of the track and place the cart’s rubber bumper (Force Sensor end) against the end stop.

    Post

  7. Spin the chair and start recording. Let the chair spin down to a stop and then stop recording.

  8. Apply a curve fit to the data to determine how the centripetal acceleration and force are related to the angular velocity. For the quadratic fit, open the curve fit editor at right in Capstone and lock the coefficient B = 0.

 This forces the fit to Aω2 + C. From the curve fit, what is the radius?

  1. In which direction are the centripetal acceleration and the centripetal force?

Further Study

  1. Move the end stop 5 cm closer to the center of rotation. Repeat the experiment.

  2. Continue to move the end stop closer to the center in 5 cm increments.

  3. How does the centripetal force depend on the radius?

Sample Data

Both the centripetal acceleration and the centripetal force are pointing toward the center of the circle (they are negative) and are proportional to the square of the angular velocity.

a = -0.383ω2 – 0.0530

F = -0.0966ω2 – 0.00596

m = 0.25 kg

F = ma = 0.25(-0.383ω2 – 0.0530) = -0.096ω2 – 0.013

The radius is 0.383 m because a = rω2.

Newton’s Second Law Demonstration

Equipment:

  • Smart Cart

  • Accessory Hook

Learning Outcome:

Forces and Accelerations of objects have a linear relationship that relates the mass of an object being accelerated to an unbalanced force acting on it.

Experimental Setup:

  1. Take your Smart Cart out of the box.

  2. Attach the hook accessory (included with Smart Cart) to the force sensor on the Smart Cart.

  3. Press the power button on the side of the Smart Cart to turn it on.

  4. In SPARKvue or Capstone, pair the Smart Cart to your computer or device. Here are a couple short videos to help you pair in either software:

    1. SPARKvue: https://www.youtube.com/watch?v=tsdHWu4quNo

    2. Capstone: https://www.youtube.com/watch?v=JGy-UG245lY

  5. In the software, you will need to create a graph of Force vs. Acceleration.

    1. SPARKvue: Under “Quick Start Experiments” choose: Newton’s Second Law

    2. Capstone:

      1. Create a Graph Display

      2. Select measurement of [Force] for the y-axis

      3. Select measurement of [Acceleration – x] for the x-axis

      4. In the sampling control panel, press the “Zero Sensor” button

Before you collect data, practice rolling the cart in a forwards and backwards motion by only holding on to the hook. You want to apply a force along the cart’s x-axis, and have the cart roll only along this direction. This is made easier using a PASCO track to keep the cart moving in one direction, but not necessary for the demonstration. (Hint: Try not to wiggle or knock the Smart Cart hook as this will result in extraneous data points.) 

Data Collection:

  1. Press the record data button

  2. Holding only the hook, roll the Smart Cart forwards and backwards in the x-direction.

  3. Repeat this motion a few times to generate enough data points to see the graphical relationship.

  4. Stop data collection

Data Analysis:

  1. Turn on the ‘Linear Fit’ tool

  2. This relationship shows that there is a proportionality constant between the unbalanced force, and the Smart Cart’s resulting acceleration.

  3. The proportionality constant is the mass of the cart.

Add mass to the Smart Cart and repeat data collection for the new system mass.

Sample Data:

This data was created with a Smart Cart that measured .246 kg, for an error around 2%.

Average and Instantaneous Velocity and Speed

  1. Take your Smart Cart out of the box.
  2. Turn it on and open your choice of software: SPARKvue or Capstone.
  3. Wirelessly connect to the Smart Cart. Change the sample rate of the Position Sensor to 40 Hz.
  4. Open the calculator in the software and make the following calculation:
‎speed‎=abs([Velocity, Red (m/s)‎])       with units of m/s
  1. Create a graph of Velocity vs. Time and add a second plot area of speed vs. Time and add a third plot area of Position vs. Time.
  2. Mark a starting point with a piece of tape.
  3. Start recording. Push the cart about 20 cm out and back, ending at the same point where you started.
Analysis
  1. On the Velocity vs. Time graph, find the maximum positive velocity.
  2. What is the instantaneous velocity at the point where you reversed the cart?
  3. What is the average velocity over the entire motion of the cart? Highlight the area of the Velocity vs. Time graph during the time of the motion and turn on the mean statistic.
  4. What is the average speed over the entire motion of the cart? Highlight the area of the speed vs. Time graph during the time of the motion and turn on the mean statistic.
  5. What is the difference between speed and velocity?
Sample Data
The instantaneous velocity when the cart reversed was zero.
The average velocity over the whole trip was zero because we started and stopped in the same place.
The average speed over the whole trip was 0.36 m/s.
Speed is a scalar that is the magnitude of the velocity. Velocity is a vector and has both magnitude (speed) and direction.

The Differences Between Velocity and Acceleration

  1. Take your Smart Cart out of the box.

  2. Turn it on and open your choice of software: SPARKvue or Capstone.

  3. Wirelessly connect to the Smart Cart.

  4. Change the sample rate of the Smart Cart Position sensor to 40 Hz.

  5. Set up a graph of Velocity vs. Time and Acceleration vs. Time using the Position sensor’s Velocity and Acceleration.

  6. Make an inclined plane by placing the top edge of one textbook on top of a second textbook.

  7. Put the Smart Cart at the bottom of the incline, with its force sensor end oriented up the incline.

  8. Start recording and push the cart so it just barely reaches the top of the incline and then rolls back down. Stop recording when it gets back down.

  9. Examine the graphs and determine where the cart is:

    1. going up the incline.

    2. going down the incline.

    3. at the top of the incline.

For each of these cases, is the velocity positive, negative, zero, and/or constant? Is the acceleration positive, negative, zero, and/or constant?

  1. When the cart is going up the incline, which direction is the velocity? Which direction is the acceleration? Is the cart accelerating or decelerating?

  2. When the cart is at the top of the incline, the velocity is zero. Which direction is the acceleration? Is the cart accelerating or decelerating?

  3. When the cart is going down the incline, which direction is the velocity? Which direction is the acceleration? Is the cart accelerating or decelerating?

  4. On the Velocity vs. Time graph, find the slope of the straight-line portion. Compare this to the acceleration on the Acceleration vs. Time graph.

Sample Data

When the cart is going up the incline, the velocity is positive (up the incline) while the acceleration is constant and negative (down the incline). The cart is decelerating.

When the cart is at the top of the incline, the velocity is zero while the acceleration is constant and negative (down the incline). The cart is accelerating.

When the cart is going down the incline, the velocity is negative (down the incline) while the acceleration is constant and negative (down the incline).

The slope of the Velocity vs. Time graph is -1.57 m/s2. The average acceleration from the Acceleration vs. Time graph is -1.577 m/s2, which is 0.6% different from the slope.

The Effect of Learning Through Inquiry: A Blog Series

Who am I?

Hello World! My name is Maayan, and I am another co-op student at AYVA. I’m currently studying biochemistry at the University of Guelph, which is how I ended up on the AYVA Team. A bit more about me: I do not have any cute pets, but I do have two younger brothers. I’m interested in science, especially all the cool discoveries that can be made to improve the human condition. Outer space is rad. I can talk about Mars colonies for hours on end.

How did I get into science?

As a wonderfully sweet little child, I frequently stole my brothers’ toys. I built Lego castles, controlled toy cars, and appropriated (stole) puzzles by the box. I liked building things, and I liked breaking things down to see how they worked. As I continued to grow into an adolescent, I enjoyed reading science fiction, enough to finish all the books my school library had.

Eventually, as I skipped on through life, I was assigned to do a school project on an important Canadian. I chose Julie Payette, an astronaut (and currently the Governor-General), and my interest was born. It was amazing to me that people had gone to the moon, and now different countries were collaborating on the International Space Station for scientific research. For the first time, I felt that people could come together for a cause to further humanity. The five-dollar bill is still my favorite: it has the Canadarm2 and the astronaut on it. To this day, I smile whenever I see one.

In high school I realized that astronauts couldn’t have gotten to space without a team of people down on earth who helped solve problems, and just because their jobs were less flashy (and got less camera time) it did not mean that they were any less important. Anyway, I liked biology (humans!) and enjoyed learning chemistry (and about the universe). I couldn’t decide which one I liked better, so biochemistry is the major I chose. No one seemed to be offering xenobiology or astrobiology courses at the time, but I hope someday they will.

What’s Next?

Back to the blog, I will be writing a few articles on teaching science through inquiry. This is important for future STEM-ists since teaching STEM is only a step before understanding STEM. After all, every inventor, scientist, engineer, mathematician, technologist, and astronaut started as a student.

Nice to meet you, and I hope to write again soon,

Maayan

Going Wireless: Shifting Augustana’s First-years Labs

Written by: David King, University of Alberta – Augustana Campus

The Augustana Campus chemistry labs have traditionally been perfectly acceptable, but have yielded somewhat standard chemistry experiments with very typical analysis. As a satellite campus of the University of Alberta, located in Camrose, Alberta, we have strived to be almost an extension of our North Campus sibling, which has proved problematic within the constraints of a 100 kilometers distance. Recently, things have changed. Last summer, we diverged from this straightforward and customary path and decided to do something slightly different. Along with our newly renovated labs—that encourage thought and collaboration—we have fundamentally changed our first-year chemistry lab experiments, which mean that different analyzation techniques are needed. Gone are vitamin C titrations with Tang and tablets, replaced by extraction techniques and spectral analysis. Hand-held spectroscopes have been replaced with a fiber optic cable in a light emissions lab while also adding a light measurement for chemiluminescence.

Our previous vitamin C laboratory experiment was based in a traditional vein, where titrations were used to determine the vitamin C content in both Tang (a powdered orange drink very few students today have ever experienced) and 500mg vitamin C tablets. Being a “traditional” lab exercise meant that most students likely had seen this done in high school or had done this very titration themselves. Our goal was to create an experience where the students learn a new analytical technique by extracting vitamin C from a pepper, then determining the vitamin C concentration from a standard calibration curve on a PASCO Wireless Spectrometer. All of these skills are taught in the first week of this exercise. Week two is all about the inquisitive nature and enthusiasm of the first-year chemistry students. We wanted them to start critically thinking about what they read and whether or not it is scientifically sound, and we also wanted students to gain confidence in their research abilities right away, both in a laboratory setting and with data analysis. The idea is that students would formulate a research question and then create a hypothesis to test in the lab to add to their skills. Since the PASCO Wireless Spectrometers allow us to keep data sets, we could use the same calibration curves throughout the testing.

Student Myths Tested:

  • Different cooking methods affect on Vitamin C
  • Different storage methods affect on Vitamin C
  • Freshly squeezed vs. prepackaged juice
  • Over the counter vitamin C supplements vs. natural sources
  • Comparing vitamin C content of fruits and vegetables from different international origins

Light emissions lab experiments can be tedious at best. You need to constantly be looking through a hand-held spectroscope, which is exactly what we were asking our students to do. Also, we were looking at lights, flame tests and emission tubes with said spectroscopes. Throughout all of this, we weren’t asking the students to really do anything else, chemically speaking. Chemiluminescence and chromatography columns were two things we decided to add into our updated labs, along with the fiber optic cable accessory for the Wireless Spectrometers (as well as scaling back the spectroscope use). In the first part of our experiment, students would activate a glow stick and add the content to our 3D printed Light Calorimeter, then read the light emitted using the PASCO Wireless Light Sensor. From here, students would take the glow stick content and run it through a silica gel column to remove the chemical that activates the “glow”, then read the light emitted again. Peroxide and sodium salicylate would then be added to get the “glow” to return, and one last reading on SPARKvue would be taken.

By using this method, we wanted students to learn not only about columns and their ability to separate mixtures but also to get comfortable learning how to collect data using a sensor and a data logger (in this case an iPad). In the second part of our experiment, we still use traditional light emission tubes (Argon, Helium, etc.) where we use spectroscopes to obtain the emission spectrum lines. For the hydrogen tube, however, we set up the fiber optic cable accessory and the PASCO Wireless Spectrometer to get the most precise emission light spectrum we can. Ideally, the students learn both techniques but come away with the appreciation for the newer tech.

Changing these two experiments to incorporate PASCO equipment and using different techniques has allowed the students to get a more modern feel for newer types of equipment and techniques that are more advanced than your “standard chemistry type” experiments.

Since the wireless sensors are easily incorporated into our lab designs, we have set our sights on adding the brand new PASCO Wireless Colorimeter to our forensic based Escape Box Lab to give students an idea how an analysis of this type could be performed in the field.

We also have a unique laboratory based three-week course for non-science majors that utilizes the PASCO Wireless CO2 sensor in an interesting way. Our laboratory future is both bright and innovative, and more importantly, possible, with the tools from PASCO at our disposal.

 

PASCO products mentioned in this article:

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    Gurpreet Sidhu | Physics Instructor | University College of North | The Pas, MB

  • Wireless Spectrometer Big Hit With Students – PASCO’s wireless spectrometer has been utilized very well by our earth science and physical science teachers. It’s an excellent piece of equipment and we have very much enjoyed its addition to enriching our classroom. It definitely brings students to a higher level of understanding wave interaction at a molecular level.

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  • Datalogging Activities are Cross-Curricular

    Throughout the province of Nova Scotia, PASCO’s probeware technology has been merged with the rollout of the new P-6 curriculum. We chose a number of sensors for use with our project-based activities. Both the functionality and mobility of PASCO’s dataloggers enable students to collect authentic, real-world data, test their hypotheses and build knowledge.

    What we find important to a successful implementation and adoption by teachers is showing that the probes are not a ‘standalone technology’. The datalogging activities are very cross-curricular and can incorporate math, english, science, and geography outcomes.

    We are excited to learn more about PASCO’s new weather sensor because our students enjoy projects where they can share and compare their data with weather stations from around the world and be part of a global community.

    Mark Richards | Technology Integration Consultant | Annapolis Valley R.S.B. | Nova Scotia

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