Physics in a Box
Thanks to their instructors’ crafty hack, students in online labs use items like rubber bands, paperclips and LEGOs to solve complex physics problems
By Tracy Staedter
Biomedical sciences major Madeline Gwinn received a small package near the end of May, shortly after enrolling in an Intro to Physics summer course. In the mailed box were rubber bands, marbles, LEGO blocks, metal binder clips, fishing line, kite string, tape and a protractor. It had been sent by Melissa Vigil, physics laboratory supervisor, and Mike Nichols, teaching laboratory associate, as a way to teach the lab portion of the course remotely. “I was like: I don’t know how this is all going to work,” says Gwinn.
Normally, the course relied on more expensive lab-based equipment and sophisticated sensors to teach fundamental physics concepts, including kinematics, energy, momentum, and torque. But when it became apparent that spring’s COVID-19-driven shift to remote learning would extend into summer, Vigil and Nichols put together a box of objects that could be combined to make a variety of gadgets, like pulleys or rolling carts. With standard sizes, weights and masses, the objects were good for solving equations, too.
Students learned to break down complex systems and extract the information needed to understand how these systems worked. They also got a sense for how some of the pioneers of physics — think Leonardo da Vinci and Sir Isaac Newton — answered fundamental questions around motion, flight and other processes without the help of modern technology. It’s a problem-solving strategy that connects physics to real life, says Vigil.
“How are you going to tackle the big problems? Here’s a pile of stuff in front of you. What are you going to do with what you have?” she says. Whether it was a remote learning or hybrid learning environment, Vigil says, “I was not going to let the students lose that ability.”
Back to Basics
On the ice, professional figure skaters amaze audiences with their astonishing ability to spin. They begin their rotations with their arms outstretched and then pull them in to speed into a whirling blur. This action exemplifies angular momentum, which describes a spinning or pendulum-like motion. Angular momentum is a product of how fast an object is moving and how the object’s mass is distributed about its rotational axis. For a skater, the axis is the center of the person’s body. But for a bird wing in flight, for instance, the axis is the animal’s shoulder.
Vigil and Nichols typically teach aspects of this concept in a lab setting using a device called a “rotational motion apparatus.” It’s a reconfigurable device about 18 inches tall that looks like a capital letter “T” and spins on its vertical axis. For one experiment, students put counterweights on each end of the T and cause it to spin like a skater. A sensor on the device collects data needed to calculate the kinetic (motional) energy of the spinning T. Students can produce different results by moving the counterweights on the T closer to the shaft, just like a skater drawing her arms in close to her body.
The apparatus was too expensive — $100 each — to buy one for every student and ship it to their homes so Vigil and Nichols turned to Legos. In the lab kit, students found instructions for snapping together vertical rows of the colorful bricks to form an outstretched bird wing. As formed by strips of Legos, the wing is narrow at the shoulder joint and wider across the middle. The students weren’t trying to create an object that spun on an its axis. Wings oscillate back and forth or up and down. But when it comes to flying fast or slow, the distribution of mass along the wing matters in the same way that the position of a figure skater’s arms influences how fast she spins.
To calculate the potential energy the Lego wing would possess when flapping or soaring, students extracted data — such as the mass of each strip of Legos and its distance from the axis, or shoulder joint — and then plugged that data into a formula. Even without a sensor-equipped apparatus, students at home saw they could solve a physics problem with limited amounts of equipment. “We’re taking a bug and turning it into a feature,” says Vigil.
In another instance, the students built a rolling cart from Legos blocks. The first week, they put it on a flat surface and also on a ramp, analyzing its kinematics and creating graphs, pictures and solving equations related to kinematics and motion of mass. A couple of weeks later, they used the cart on a flat surface and on a ramp to study forces and Newton’s laws of physics. A couple of weeks after that, they used the cart on a flat surface and on a ramp to learn about energy and momentum.
“By looking at the same system again and again, hopefully the students will see that they have choices about how to tackle a problem,” says Vigil. “They can pick the one that makes the most sense to them.” And they can use other options to check that their first answer is correct.
For the fall semester, Vigil and Nichols continue to teach the lab with 50 percent of the work being done remotely. Instead of sending a lab kit, they asked students to use common household objects — such asstring, paper clips, clothes hangers, ceramic cups, and even some dried fruit snacks — for their home-based projects. The instructors also asked students to purchase an inexpensive gadget called an iOLab Wireless Lab System, which replaces the Lego cart. This smartphone-sized device has built-in sensors that measure force,acceleration, velocity, rotation, light, sound, temperature, pressure and more and transmits real-time data wirelessly to a computer.
For Gwinn, who took two physics classes this summer, the remote learning experience taught her that there was never one way to approach a challenge. “You’re not thinking, ‘Oh, this is how it has to be done. Your way is not wrong.’ It’s just a different approach to getting there,” she says.
