### Notes:

The Atwood's Machine Interactive is an adjustable size file that displays nicely on just about any device - on smart phones, tablets such as the iPad, on Chromebooks, and on laptops and desktops. The compatibility with mobile phones, iPads, other tablets, and Chromebooks make it a perfect tool for use in a 1:1 classroom. It can be used in full-screen mode (click the hot spot in the upper-left corner of the iFrame window) or its dimensions can be adjusted to just about any dimension by dragging the lower-right corner of the iFrame.

### Teaching Ideas and Suggestions:

This Interactive should be reserved for later stages of the learning cycle on Newton's second law of motion. It is intended for courses in which two-mass systems are part of the curriculum. The Interactive provides an environment for investigating the motion of a two-mass system. Two basic two-mass systems can be explored. By default, the Interactive opens as a modified Atwood's machine. A low-friction, wheeled cart is on a table and connected by a string to a mass that hangs over a pulley. Once the Start button is pressed/clicked, the hanging mass accelerates the cart. The distance traveled and time of travel is reported and can be used to determine the acceleration. The amount of mass that is suspended over the right-side of the pulley can be altered by clicking/tapping on one of the blue masses. The system can be reset for additional trials by dragging the wheeled cart to a desired position along the table.

Tapping/clicking on the non-wheeled block will turn the frictionless system into a modified Atwood's machine with friction along the horizontal surface. Tapping.clicking on the red mass will turn transform the Interactive into an Atwood's machine with two masses connected by a string that stretches over a pulley.

### Related Resources

There are only a couple of resources at The Physics Classroom website that serve as very complementary supports for the Atwood's Machine Interactive. These include:
Lesson 2 of the Newton's Laws  Chapter of the Tutorial is a necessary pre-cursor to the topic of two-nass systems. The following page will be particularly useful in the early stages of the learning cycle on two-mass problems:

Double Trouble

• Labwork:
Simulations should always support (never supplant) hands-on learning. The Laboratory section of The Physics Classroom website includes several hands-on ideas that complement this Interactive. One notable lab idea is ...

Modified Atwood's Machine

Visit The Laboratory.

Additional resources and ideas for incorporating the Atwood's Machine Interactive into an instructional unit on Newton's Laws of motion can be found at the Teacher Toolkits section of The Physics Classroom website.  Visit Teacher Toolkits.

### Credits

The Physics Classroom would like to extend a special thanks to Nerd Island Studios for the creation of this HTML5 Interactive. Visit http://www.nerdislandstudios.com to see more great stuff by Nerd Island Studios.