Senior Physics students traveled to the local curling rink to explore friction, momentum and collisions. Students were asked to design two different experiments to find the coefficient of friction between the curling rock and the ice (for both pebbled and swept ice). Another goal of the lab was to determine whether a collision between two curling rocks was an elastic collision.
To determine the coefficient of kinetic friction, students used the PASCO Wireless Motion Sensor to measure the initial velocity of the curling rock that was launched. Using the measured displacement and Kinematics equations, students calculated the acceleration of the curling rock, and the coefficient of kinetic friction between the rock and the ice.
Students used a similar setup to determine whether the collision between the curling rocks was elastic.
Using the PASCO Wireless Motion Sensor allowed for real-time accurate measurements in a chilly, fun lab (with all data collected within an hour).
Life has been very interesting for the past 18 months. Did I say interesting? I meant challenging. With a global pandemic in force, how does education adapt? In my area, students had several months of online only learning, followed by online four days a week, then 3 days a week. Some students had full-time school, but they did only 2 classes a day. One class for the entire morning and one in the afternoon. New classes roughly every 10 weeks. How do you teach under these conditions? How do you teach science under these conditions? How do students learn under these conditions?
This blog won’t focus on that though. We are back at full time regular school (albeit with masks) for the first time since March of 2019. The focus is how do we reengage students? How do we bring back that sense of wonder and amazement of the world around them? For me, the answer is almost always the same; do hands on work. Experimentation is science and that is where the magic happens.
Once the dust settled of courses being filled, I knew I need students doing lab work. I couldn’t wait too long. It didn’t need to be anything complicated or deep, I just needed them to be hooked. Enter my PASCO Spark, the MatchGraph app and some Smart Carts.
Just bringing out the equipment got the students excited. “What are those?” I heard more than once. “Do we get to use them?” We did a quick run through and started on the first graph. The energy in the room was off the charts. There was so much buzz; arguments on who could do it better, what were they doing right, what were they doing wrong. This is what a classroom should be and such a simple way to get it.
Soon students were mastering the first linear graph and were looking very proud of themselves. I then told them there were more graphs. Deflation, curiosity and excited sped across their faces (at least their eyes) and they quickly started trying them. Carts were flying across the tabletops. 45 minutes passed in a blink and when I told them class was coming to an end and the equipment needed to be put away there were actual groans. They wanted to keep going! More than one student asked if we were going to use the equipment again. My answer was simple: tomorrow.
The students are hooked. They are excited to be learning. All it took was a little bit of learning play with my Smart carts and PASCO MatchGraph.
One of the hardest things about teaching online during this pandemic has been ensuring student engagement. When my physics class moved online, I knew I wanted to somehow continue the lab component but wasn’t quite sure how… until I learned about shared sessions in SPARKvue.
Without a doubt, remote labs were not going to be as hands-on as they were in person, but students should still have the opportunity to engage in the other practical applications of labs like making observations and analyzing data. A shared session in SPARKvue allows students to see data being collected in real time as if they were doing experiments themselves. I recently used this feature for a circuit lab in my Physics class.
I set up a circuit using the modular circuits and pointed a webcam on it so the students could see the circuit I was building and manipulating. I then started a shared session on SPARKvue and the students all joined in to see the voltage and current readings. As I made changes to the circuits, I had students write various predictions in the chat of our meeting room. The ability to predict and then see what actually happens in real time reflects what my students would do if they were engaging with this lab in person.
Doing this lab remotely not only allowed the students to predict, observe, and analyze; it actually opened up an avenue for more enriched discussions due to it’s collaborative nature and engaging the entire class at the same time. When the data didn’t exactly match a prediction, I could point to aspects of the circuit through the webcam and connect what we were seeing to the data being shown.
The ability to predict, observe, and analyze is one of the key features of any science lab. By pairing a data collection program like SPARKvue with a webcam and the modular circuits kit (or other PASCO sensors), students can observe how data is being collected and engage in the process of scientific exploration of the concepts they would otherwise only see written on a page. SPARKvue is changing not only the physical classroom but also the virtual classroom into a more engaging, thought-provoking, and dynamic environment for learning.
Projectiles is a major concept in every physics class, but finding a lab activity to demonstrate this concept can be quite difficult. I have tried a number of ideas in the past, such as rolling balls off tables, firing nerf guns (that seem to never shoot consistently), launcher-building competitions, and so many more. While these activities were okay, they were all limited in terms of measurable variables. The projectile problems I give my students often have some sort of initial “launch” velocity, proves to be the hardest thing to measure in a practical setting.
With the Wireless Smart Gate, this is no longer an issue. The Smart Gate will seamlessly measure the speed of any object that passes through it. Now when my students roll a ball off a table, the ball travels through a Smart Gate first giving them the speed at which the ball leaves the table. Before the Smart Gates, students would have to predict the speed of the ball based on the ball’s range, but they never had a value to compare their predictions with. The Smart Gate allowed for a comparison and when students compared their values, they were amazed at how a value calculated on paper translated into a real-world measurement.
Angled launches remained a stumbling block for me. Rolling a ball through a Smart Gate is easy but launching one through? Pasco has angled projectile launchers available to purchase, but I thought I would build my own to see how feasible it would be to have my students eventually build the same. I wanted a product that would launch a ball through the smart gate at various angles so that students could see how the launch angle and speed affects ball flight.
The following pictures are of the finished product. The ball is loaded in the top of the pvc pipe where it rests on a bolt. The bolt is attached to two springs so that when it is drawn back and released, the ball is launched. The video shows the launcher in action. You can see how, as the ball moves through the smart gate, the Smart Gate automatically records the velocity of the ball. The dual beam technology in the new Smart Gate allows for different sized balls to be used, as the velocity is based on the time difference between the two beams. The old photogates only had one beam and you had to calibrate the sensor to the specific size of the object moving through the beam.
Being able to instantly measure the velocity of a projectile before it flies through the air is extremely valuable in the application of this concept. While there are things I would do differently in the construction of the launchers, students were able to see how the different velocities and angles affect the range of the projectile. Once again, students predictions matched measured values closely and they were again amazed at the ability to see this difficult concept in action.
Inquiry. The buzzword of the day. How does it relate to science? Easy; it is science!
How to make it meaningful is the real question. How do we engage students and make it relevant to them? What can draw them in? What will impact them at a deeper level?
For me, it was car crashes. Momentum involves studying collisions and there are a lot of crashes with teens learning to drive. Add to the fact that my city is a giant hill and the lesson just kind of built itself. We would study materials to see what could protect you in the case of a crash.
Smart Carts, SparkVue and a random assortment of materials. Styrofoam, rubber, cotton, what would work best? The students had preconceived ideas…perfect.
I turned them loose with the barest of hints. What are you worried about in a crash? What should we measure? What situations do we need to test?
They picked random materials and got to it. The discussions were great! Arguments about what to use, how to set it up, how to measure, what to measure. They looked to me to settle disputes and I said “Work it out yourselves. You can do this.” Here’s what they came up with.
Doing the two graph setup measuring velocity vs time and force vs time they could identify when the collision took place easily. They could use the area of the force-time graph to calculate impulse.
The results surprised them. That lead to more questions. And that is what science, and inquiry, is all about.
I’ve been teaching physics for years and for most of the years that meant one thing: ticker tape. Don’t get me wrong, there is a certain elegance to labs using ticker tape; there just isn’t as much depth. Enter the PASCO Smart Cart and SparkVue software.
I’ve had the carts for a few years now and I keep learning more things to do with them. I wanted students to go deeper into Newton’s laws but how could I do that with the Smart Carts and SparkVue? Here’s what I came up with.
I took my old set-up from the ticker tape days. Have a cart pulled across a table pulled by a hanging mass over a pulley. Change the amount of mass on the cart and the amount pulling the cart. Calculate the acceleration using kinematics. Compare the mass times the acceleration to the weight hanging over the edge.
That set-up is lowish friction, which we could hand-wave away, but I never liked doing that. If we used the carts on a track with the Super pulley would I get better results? Indeed, I did. Measured accelerations were within 10% of theoretical. Could I do better?
I attached the hook to the carts and used the force sensor to measure the tension pulling the cart. Using the data from the force sensor I got within 1% of expected values! This is great accuracy and a starting point for going deeper. Why does the force sensor start with the force of the hanging mass and then drop? Why does the force sensor data give better data then using the values of the hanging mass?
The old lab changed the mass on the cart and the mass hanging off the edge to compare the effects of changing the mass of the system or changing the force of the system. Good but not great. Now I can do the lab over the pulley or run the string through the end stop for increased friction. The students can compare different variations of the set up in the same amount of time it took with the ticker-tape.
With ticker-tape it took a long time and didn’t go very deep; basic understanding only. Now with the Smart Carts and SparkVue we can go deeper, quicker. Isn’t that what we are after? Critical thinking and deeper learning? PASCO’s products offer a chance for that and I am grateful for it.
We high school physics teachers tend to associate the right-hand rules with electromagnetism. As a student, my first encounter with a right-hand rule was when I was introduced to the magnetic field produced by the electric current in a long, straight wire: if you point the thumb of your right hand in the direction of the conventional current and imagine grasping the wire with your hand, your fingers wrap around the wire in a way that is analogous to the magnetic field that circulates around the wire.
I only later discovered that this same rule can be applied to rotational quantities such as angular velocity and angular momentum. The topic of rotation has become more important in AP physics when the program was updated from the older Physics B program. Strictly speaking, AP Physics 1 does not include the use of the right hand rule for rotation, but I have found that introducing it actually helps solidify student understanding of angular vectors.
Describing the direction of rotation as being clockwise or counterclockwise is helpful only if all parties involved have a common point of view, which is ideally along the axis of rotation. As with left and right, clockwise and counterclockwise depend on your point of view. This is why it is often preferable to describe translational motion in terms of north, south, east, west, up, and down, or with respect to a defined x-y-z coordinate system; directions can be communicated unambiguously, provided that everybody uses the same coordinate system.
It is precisely for this reason that the right hand rule can (and should) be used for rotational motion. Consider the hands of an analog clock. Assuming that the clock is a typical one, it will have hands that turn “clockwise” when viewed from the “usual” point of view, but if the clock had a transparent back and you were to view it from the back you would see the hands turning “counterclockwise!” The observed direction of rotation (clockwise or counterclockwise) depends on the observer’s point of view.
Instead of using clockwise and counterclockwise, we can describe the direction of rotation with a right hand rule: if you curl the fingers of your right hand around with the direction of the rotational motion, your thumb will point in the direction of rotation, which will be along the axis of rotation. Applying this to the above we find that when viewing a clock from the front, the rotation of the hands is three dimensionally into the clock (away from the observer), and when viewing a clock from the back side, the rotation of the hands is three dimensionally out of the clock (toward the observer). If two people view a transparent clock at the same time but one observes it from the front while the other observes it from the back (i.e. the clock is between the two people who are facing each other), they will disagree on which way the hands turn (clockwise or counterclockwise) but will agree on this direction if both use the right hand rule convention to describe the direction of the rotational motion – both observers will agree that it is directed toward the person viewing the back side of the clock.
When first learning about the right hand rule, students are often initially confused, with many students failing to grasp why such a rule is even useful in the first place. Before introducing the right hand rule I like to begin by holding an object such as a meter stick while standing at the front of the classroom. I then rotate the meter stick through its center so that the students claim that it is rotating “clockwise” when asked. Being careful to keep the rotational motion as constant as possible, I then walk to the back of the room. It’s important that the students see that at no point did I stop the rotation of the meter stick – it is still turning the same way as before, and yet at some point each student finds that they must turn around in order to continue to see it. Many students are astonished to see that the meter stick is now rotating counter clockwise from their (now reversed) point of view. This helps establish the need for a better way to describe rotation.
I then introduce the right hand rule and go through a couple of examples. Traditionally, this would have been the end of it, but last year I was able to take advantage of my newly acquired PASCO Smart Cart, which has a wireless 3-axis gyroscope (i.e. rotational sensor). The coordinate system is fixed with respect to the cart, and is printed on the cart itself, but I like to make this more visible by attaching cardboard cutout vectors onto the cart which make the axes more visible to the students while I hold the cart up for them to see. I then set up a projected display of the angular velocity of the cart along each axis simultaneously. I then ask the students how I must turn the cart in order to get a desired rotation of my choosing (i.e. ±x, ±y, and ±z).
I really like how the carts, along with the live display of the 3 angular velocity components make the admittedly abstract right hand rule so much more concrete. Seeing the display agree with our predictions makes it so much more real and is much, much better than me merely saying “trust me.” I have found that introducing and using this right hand rule with rotation has made using this same rule much more natural when using it to later relate the direction of current flow and the magnetic field.
It was the shot heard across Canada. There were a lot of factors that made Kawhi’s buzzer beating basket so remarkable. Aside from there being no time left on the clock and the weight of a sport’s nation on his shoulders, Kawhi had to overcome the backward momentum that is inherent in a ‘fadeaway’. The purpose of a fadeway is to create space between the shooter and defender(s), which was a necessity for Kawhi as there were several seriously tall 76ers trying to screen his shot.
Over-coming the fadeway’s backwards momentum is no easy feat as it requires players to quickly calibrate in their minds the additional force that is required to successfully sink a basket, which for most mere mortals is not intuitive. The shot is so challenging that only a handful of NBA basketball players have been able to reliably make this shot; and we’re talking the great players such as Michael Jordan, Lebron James, Kobe Bryant and of course Kawhi Leonard.
The video below provides an extreme example of backwards momentum with a soccer ball shot from the back of a truck
Investigating Kawhi Leonard’s shot in the lab
In addition to backwards momentum there were many additional physical factors at play such as the angle of the shot and gravity. Investigating all these forces in a single activity would not be practical. Fortunately most of these forces can be isolated and explored in the lab using PASCO sensors, software and/or equipment.
Exploring The fadeaway’s negative momentum using PASCO
PASCO offers an intriguing and affordable solution to model the dramatic effect of a fadeaway’s negative momentum on projectile distance. PASCO’s mini launcher will consistently launch projectile balls the same horizontal distance for a set angle, assuming that the launcher is stationary. If however, the launcher is placed on PASCO’s frictionless cart, the force of pulling the trigger will cause the cart to move backwards at a velocity that can be measured using the motion sensor. Students will be surprised to see that even though the cart travels just a few centimeters, the overall projectile distance is significantly reduced. This can be a very simple demonstration or an in-depth quantitative analysis that factors in the projectiles initial angle and velocity, the time of flight and even the k-constant of the spring.
Other Forces Affecting a Basketball Shot
Momentum and Explosions
When a basketball player takes a jump shot (as with a fadeway), the player and the ball could be viewed as 2-object linear system if you ignore other outside forces such as gravity. What’s interesting, and perhaps not apparent to many students, is that the basketball will exert an equivalent force to the player as the player is exerting on the basketball (Newton’s 3rd Law). Of course because of the very significant inertia (mass) difference between the two objects, the basketball will accelerate at a much fast rate than the player. The player however will experience some acceleration in the opposite direction to that of the basketball.
Using Smart Carts to explore Momentum and Explosions (Free Lab)
The Wireless Smart Carts are equipped with an exploding plunger. Multiple 250g bars can be added to one cart to skew the masses. The velocities of both carts are measured using the cart’s internal position sensors enabling students to determine that momentum is conserved in a linear exploding system.
The player’s force on the basketball will be equal to the opposing force of the basketball onto the player. Of course most students will consider this a ridiculous proposition until they prove this for themselves.
Using Smart Carts to explore Newton’s Third Law
There are several ways the carts can be used. The simplest activity is for two students to have a tug-of-war using the internal force sensors of two Smart Carts and an elastic band as depicted in the image. The equal but opposite forces will be confirmed, however in relation to a basketball player taking a shot, it has some shortcomings as the forces are pulling as oppose to pushing.
An equally simple activity, and one more relevant to the basketball shot scenario, is to collide two Smart Carts (with magnetic bumpers attached to their force sensors). As both carts have equivalent masses, students may not be surprised to see the impact forces are identical. However, what will probably surprise your students, are the force measurements that occur during a collision when one cart is weighed down with one or more 250g masses. Using their intuition, most students will speculate that one of the carts will experience a much greater force than the other. Of course, Newton’s 3rd Law will triumph and the forces will be identical.
What goes up must come down. This is true of course for all earth bound objects (including basketballs) due to the ever present force of gravity. Without gravity the trajectory of a basketball player’s shot would be straight to the ceiling of the arena, where most of the fans would be viewing the game.
Exploring the accelerating force of gravity using the Motion sensor
PASCO offers several technologies and techniques for measuring gravity including the Wireless Smart Gate and Picket Fence and the new Freefall apparatus. Both of these techniques are accurate and precise means to measure gravity. A third technique and one more appropriate for relating to a basketball shot is to measure the position of a vertically tossed ball and then have the software derive an acceleration graph from this data. Statistics, including the Mean of the acceleration plot can be calculated by the software for the period when the ball was in freefall as shown in the graph.
I recently hosted my first ever professional development event. Usually, at the local level, there aren’t many opportunities for science types. There just aren’t enough of us and we specialize so there isn’t much common talk beyond ‘how can we get the students to love and learn science more?’. That is why I went out of comfort zone to host an event on sensors. I’m still not an expert on my physics equipment from PASCO let along the sensors for the other branches but I thought it was worth the shot.
How do I do a pro-d event that engages the audience? How could I hook the teachers in attendance? The answer was easy. Not for me to stand there and talk at them. No! They needed to do science! They needed to use the sensors. So, that’s what we did.
I set up several stations in my room. One for physics, one for bio, one for chem and outside for earth science. Each station required the use of an appropriate sensor (motion, CO2, pH and weather) and a task. I gave them as little instruction as possible beyond how to use SPARKVue. I wanted them to experience what their students would.
I expected only my department to show up. That is still 13 people. I had middle school and elementary teachers show up as well. How would they do? The hours flew by. I didn’t need to worry about filling the time; we needed more. There was a buzz that you don’t hear at staff meetings. They were engaged. They were loving it. They were hooked on sensors.
What I loved most was the talk on how they could use it for their classes. I wanted to get their ideas because they would know better than I. Every teacher left with an idea on how the sensors could be used…if only we had more.
When the day was over I was asked to host more of these. It was very easy to say yes.
I’ve been a theorist and an experimentalist at different times throughout my career. When at university, theory won out over experimental but now, as a teacher of high school, experimental easily wins. There is nothing like watching students figure out problems, deduce scientific laws and test theories. The old problem was the equipment.
What can I do with ticker-tape?
How responsive are the thermometers?
How reliable is the data?
How big are the errors?
Is it going to work?
But now, with my PASCO equipment, things are changing. I’m more excited and so are my colleagues. The students are picking up on that excitement too. The labs we’ve done for decades are being updated. However, the real joy is in designing new ones.
Since September I’ve created three new labs besides updating the other eight I do. One for kinematics, one for gravity and one for momentum. The momentum one is great because we were never able to do a reliable lab before. Using the Smart Carts and Sparkvue the kids are designing safe barriers and analyzing crashes. My favourite part of that lab is having the students figure out if movies are lying to you when they show a person getting shot, flying backwards through a window, and landing a few metres on the other side of it. We can recreate the situation with the Smart Cart acting as the bullet and looking at the forces involved.
This screenshot represents a head-on collision between two smart carts. They were released at different times to offset v-t graphs.
As I was working on the design of the labs and testing them out, my colleagues and administration stopped by. They all wanted to see what I was up to. They could see my excitement. They were infected. Two team members went away and started designing their own labs. We are talking more, sharing more and the kids benefit from it.
We can ask deeper questions because the data is more reliable and relatable. We can do so much with the carts and are figuring out more each time. Labs in physics 12 were hard because of analysis to 2-D. We are creating labs for them. The goal is a least two new labs a month. The labs are also not so cookie-cutter. They don’t always have to be quantitative. They are exploring more and, hopefully, learning more.
All of this is possible because of the Smart Carts, Sparkvue and the joy of lab design.