Iowa Alumni Magazine | April 2009 | Features

Fun with Physics

By Shelbi Thomas
Ever wonder why a ball bounces or how an airplane stays in the sky? A popular UI class addresses these and other questions about the physics of everyday life.

Bob Merlino is reading aloud a slide on projectile motion to 300 undergraduates in a Van Allen lecture hall when suddenly a tennis ball soars across the room, bounces off the back wall, and nearly pops a student in the head. Students chuckle in disbelief, but the UI astronomy and physics professor doesn't bat an eye. He hurled the ball.

Rather than drone on about how gravity affects the vertical path of a projectile, Merlino set the ball in motion to give students a memorable visual. Usually, huge lecture rooms brim with distractions—chatting, laptops, and cell phones—but in "Physics of Everyday Experience," Merlino is the distraction. Rarely five minutes of class time ticks away without another physics experiment to keep underclassmen engaged.

Merlino jokes that the introductory physics course can be hazardous to his students' health, but that's a risk more than 3,000 UI undergraduates in the last five years have been willing to take to bring science to life. Just as Isaac Newton discovered the law of gravity when an apple knocked his noggin, Merlino's students learn about the universe by being hit over the head with science.

Merlino doesn't always use projectiles. Sometimes, it's colliding cars (toy ones), high-pitched noises, or a video of a man being shot out of a cannon. No matter the experiment, Merlino's hands-on approach to physics leaves students with a strong first impression. That's important to Merlino, whose students initially sign up for the course simply to meet the university's general education requirement for physical science. For many of the business and liberal arts and sciences majors in the class, this may be the first and only time they study physics.

Without the "Physics of Everyday Experience" course, phenomena such as how rainbows are formed or why the Earth orbits around the sun may seem like a mystery. Merlino teaches his students that the way the world works isn't magic, but that through the scientific method, they can uncover the laws that govern the universe. He exposes them to the basic principles of physics—from Newton's Laws of Motion to Einstein's Theory of Relativity—and shows them how these laws are relevant to their lives.

Students appreciate how Merlino makes them participants—and not merely observers—of science. "My high school physics teacher just gave me the formulas, but Merlino applies physics to real life and gives examples of what he's talking about," says Josh Beler, a pre-business sophomore from Buffalo Grove, Illinois. "I like how he mixes it up and keeps us awake, even though it's 11:30 in the morning."

Merlino's experiments spark students' curiosity about life's little questions, from why magnets stick on refrigerators to how the police nab speeders. They also keep students on the edge of their seats. In a lesson on how to calculate an object's change in momentum (force multiplied by time), Merlino drops two glass beakers from the same height—one onto a cushion and the other onto the hard floor. The beaker that falls onto concrete shatters into hundreds of pieces, shocking the students, who didn't think Merlino would sacrifice the container in the name of science. For the professor, though, a broken beaker is a small price to pay to teach students the principle behind airbags—that a cushion causes the head to come to rest more slowly, decreasing the amount of force a person faces in a crash.

The unpredictable nature of the course might inspire some students to see Merlino as a mad scientist, but it also encourages them to recommend the attention-grabbing professor to their friends. On the website www.ratemyprofessors.com, several former students have called Merlino the best instructor they've had at Iowa. Such glowing recommendations have led to countless requests from physics teachers and textbook publishers for lesson plans—as well as overflowing classrooms for Merlino semester after semester.

Merlino's presentation of the material may get students in the door, but physics holds them in their seats. Because physics explains the patterns and rules of behavior for everything in the universe—from the smallest atom to the largest planet—students have no trouble seeing how the class applies to their everyday life. They learn to understand the world around them by combining logic and reason (thought) with observation and measurement (experiment). "Everything we know, we know because of experiments," says Merlino, and he demonstrates this point by conducting numerous tests that help his class discover answers to:

  • The reason for that funny feeling in your stomach when you ride a rollercoaster.
  • When a rollercoaster plummets down a steep hill, gravity pushes riders down while the force of acceleration pulls them up. When the rollercoaster accelerates at a certain rate, these opposing forces balance out and create the sensation of weightlessness. Though the cab moves downward, your stomach's inertia resists motion and lags behind the rest of the body to give you that sinking feeling.
  • Why the moon doesn't fall into the Earth.
  • The moon doesn't fall because it's constantly moving in orbit, and, as Newton's First Law of Motion states, an object in motion stays in motion unless an outside force acts on it. If not for the Earth's gravity pulling and bending the moon's orbit towards our planet, the moon would travel in a straight line.
  • Why a cue ball stops dead when it hits another ball head on.
  • When the two balls collide, the law of the conservation of energy—that energy can change form, but not be created nor destroyed—means that the cue ball transfers its kinetic energy (energy of motion) and momentum to the other ball.
  • Why not everything that goes up comes down.
  • If an object reaches escape velocity, it can break free of the Earth's gravity and enter into orbit. In order to meet this speed, a spaceship leaving Earth needs to travel at seven miles per second, or nearly 25,000 miles per hour.

While these questions mostly address the laws of motion, the class also studies the physics of fluids (such as what makes airplanes fly); heat and thermodynamics (or, why ice melts); oscillations, waves, and sound (the reasons why dogs hear high-pitched noises that humans can't); electricity and magnetism (such as how electricity travels from a power plant to our homes); and light and optics (in other words, how glasses and contacts correct vision problems). A final unit on modern physics introduces students to the shift of thought that occurred after 1900 when scientists discovered that Newton's laws don't work at the molecular level. That's when Albert Einstein, Max Planck, and others developed a new set of physics laws, such as the theory of relativity, that apply on the submicroscopic scale.

Though "Physics of Everyday Experience" is mostly conceptual, Merlino also asks his undergrads to flex their math skills with basic physics formulas. Many students find such tests challenging, because they require more than just plugging numbers into a formula. Merlino expects his class to know how to read and pick out the pertinent data in any given problem, and he also wants his students to use what they've learned to make up their own minds about issues ranging from nuclear power plants to global warming. "Students expect that if they know the facts, that will be enough, but it's not," says Merlino. "I expect a certain degree of intellectual involvement. I want them to think on their own."

As the old saying goes, every action has an equal and opposite reaction. That's true when it comes to our relationship with the world. We exert as much force on the Earth as it does on us, and even though the Earth's much larger mass gives it a greater influence over us, we still affect everything around us.

When Merlino teaches this to his class, he tells students, "You can move the Earth." And they will. Not literally, but through how they apply what they've learned from their UI education.