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  • Demo Highlight: Convection With High & Low Candles
  • Demonstration Highlight: Inertial Reference Frame
  • Demo Highlight: Ring and Disc on Inclined Plane
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  • New Resource: Directory of Simulations
  • New Resource: Demonstration Video Channel
  • Visit the UMD COVID-19 Dashboard
  • Physics is Phun: Flight
  • Welcome to Fall 2025!
  • Spooky Science 2025

On December 5th and 6th, UMD Physics presents Physics is Phun: The Physics of Fluids! 

Join us either day at 7PM as we talk about fluids, do a deep dive on buoyancy, feel the pressure, and much more!

Please register at https://forms.gle/byg1y7cCFQ8AXutL8

The Physics of Fluids flyer

The behaviour of gases as they're heated and cooled can be confusing, but is really important to understanding a lot of things in daily life, from the weather outside to heating a house to designing power plants... or simply to how candles burn. Demonstration I2-45: High & Low Candles in a Cylinder gives us an example of this.

 I2-45: Two small candles burn inside a clear plastic cylinder. One sits at table height, the other is elevated on a slim metal pedestal.

Read more on the Physics LecDem Blog!

 

 

Welcome back! Today we’re taking a look at a popular demonstration related to the concept of relativity.

 When we observe and measure motion, we are inevitably making the measurement against some frame of reference. An inertial reference frame is the technical term for a frame of reference in which an object is observed to have no outside forces acting on it, so that it is moving freely in space. Sometimes we have to go to great lengths to determine what such a frame of reference might be – and in the case of Demonstration P1-02, it is literally a metal frame!

 Demonstration P1-02: The Inertial Reference Frame, a large aluminum framework with a mounted winch to lift it.

Read more about this exciting demonstration and how it can be used in class in our latest blog post.

In recent years, the classic term “moment of inertia” has started to be largely retired in favor of the more descriptive “rotational inertia;” likely a good choice, as “moment” has long since ceased to have any non-time-related usage in everyday English. But call it what you will, it can be a challenging concept for beginning students to wrap their heads around.

Demonstration D2-01: Ring and Disc on Inclined Plane is a useful illustration for clarifying this concept. Two objects of similar mass and radius, a metal ring and a solid wooden disc, are placed on an inclined plane with no initial velocity. As they are accelerated by gravity, the disc quickly outpaces the ring. You can invite students to make a prediction ahead of time about their behaviour, presenting it as a race between the two objects, and invite them to discuss the results afterwards.

A wooden disc and a metal ring sit on a table next to a wooden ramp

Read more on our blog!

 

Filling up the space

The Lecture Demonstration Facility at the University of Maryland is designed to help faculty spark student interest, identify misconceptions, help students make predictions, facilitate discussion, and reinforce curricular concepts.

View our library of over 1,600 demonstrations.

In support of most classes moving to an online model this year, the Lecture-Demonstration staff are doing our part to help connect you to resources you need for teaching remotely. As one part of this project, we have begun compiling a Directory of Simulations from around the internet, organized by general area of physics. Find it under the Tools and Resources menu above, or click the image below.

Sample subsection titles: Electricity & Magnetism Simulations, Mathematics Simulations, Optics Simulations, Oscillations & Waves Simulations, Quantum Simulations, Thermodynamics & Statistical Mechanics Simulations

There are a tremendous number of simulations out there, that folks have been creating for years. We’re testing them out, choosing ones that we can confirm currently work (always a question as internet technology marches on) and that seem useful for our department’s classes. As of this posting, we have just over fifty simulations collected. Our initial focus has been on physics that is hard to demonstrate in the classroom, or experiments that are difficult to present as static pictures or live video.

This project is ongoing! As we continue to explore we will be adding more subjects and more demonstrations per subject. We also invite recommendations! If you have a favourite simulation, let us know (email lecdemhelp at physics.umd.edu) so we can check it out and add it to the directory.

We’ll have more new projects posted soon; watch the site for news!

demovideospreviewmatrix1

In our ongoing work to support remote teaching, we are pleased to announce a new resource. Over the summer of 2020, a Teaching Innovation Grant helped to create our new Demonstration Videos. These can be used for remote, hybrid, and in-person classes to present demonstrations in conjunction with class engagement questions.

The videos have their own YouTube channel, linked both here and on the Tools & Resources Menu above; check them out today!

 

Science is all about data, and our current pandemic is no different. 

Be sure to check the UMD COVID-19 Dashboard for the latest campus data and links to reopening plans and  proper safety procedures.

Keep Terps Safe - UMD COVID Public Dashboard

 

The next Physics is Phun is coming down the runway!

Join us Friday, March 7th, and Saturday, March 8th, at 7:00 PM for Physics is Phun: The Physics of Flight! as we explore the physics of aerodynamics.

Please register using this form.

Physics is Phun Physics of Flight 2025

Welcome to Fall 2025! We at the Lecture Demonstration Facility are looking forward to working with you in the spring semester.

We appreciate as much advance notice of demonstrations as you can give; but at a minimum, please remember to order your demonstrations before the order cutoff deadline.

  • For morning classes, orders must be in before 1PM the previous working day.
  • For afternoon classes, order must be in before 4AM the day of the class.

We appreciate receiving demo orders a minimum of one full working day ahead, to ensure plenty of time for preparation.  As always, we’ll meet with you before your class to answer questions, explain safety measures, and review demonstration procedures. 

Here’s to another great semester at UMD Physics!

DD Spooky Science 2025PiP Spooky Science 2025

What's New

Watch the UMD homepage for special announcements and updates.

UMD Physics Colloquia

CMNS Events

Science on Tap

LISA Symposium Public Lecture 6/23

 

Videos of past colloquia

AIP History: Women in Quantum

AIP Report: Attrition & Persistence in Undergraduate Physics

UMD Libraries Common Quandaries Workshops for Graduate Students

UMD Teaching Tech Webinars

USM Board of Regents Awards

New journal policies on name changes

APS Webinar Series: Career Development for International Physicists

APS Webinar Series: Engaging the Public through Science

APS Webinar Series: Making Physics Inclusive and Equitable

NASA Solar Dynamics Obervatory: The Sun Right Now

  neon

Check out the latest blog posts!

C4-32
Demonstrate that bodies of extremely different densities fall with equal acceleration in the absence of air friction.

This demonstration consists principally of a long glass tube containing a heavy disc and a brightly coloured feather. A nozzle and valve at one end of the glass tube allows the air to be removed from the tube using a vacuum pump. This allows the objects to fall with or without air resistance.
Operation:
  • • Turn the tube vertically while still filled with air; show that the disc drops rapidly to the bottom end, and the feather flutters down slowly.
  • • Invite students to predict how this behaviour will change when the air is removed.
  • • Connect the pump and pump out most of the air. There will be an audible change in pitch when the tube is sufficiently evacuated, after 1-2 minutes.
  • • Turn the tube vertically again, and let the students see that both now fall at the same rate.
  • • CAUTION: The tube is thick glass; please handle with care.
Background:

The key physics in play here is twofold. Absent other forces, the two objects undergo the exact same acceleration in free fall, and so will fall at the same rate. With no air in the tube, the only force acting on them is gravity, which pulls downward on each object proportional to its mass.

However, when air is in the tube, there is a second force involved: air resistance.

The force of air resistance pushes upwards on the falling objects. It depends on two factors: the surface area of the falling object, and its velocity. So the faster they fall, the more resistance they face from the air. But recall that the force of gravity is proportional to the mass of the object, and the net acceleration of an object is the result of the sum of the forces acting on it. So if two objects have similar surface area, but one has a higher mass, then the higher mass one experiences a larger downward force than the other, while air resistance will exert close to the same upward force on both, and so the heavier object then has a greater acceleration. And that’s what we see when the tube is full of air – the more massive disc falls faster than the less massive feather. Take away the air and the force of air resistance, and they fall together!
C4, I0, I4