### Notes:

The Exploding Carts Interactive is an adjustable-size file that displays nicely on smart phones, on tablets such as the iPad, on Chromebooks, and on laptops and desktops. The size of the Interactive can be scaled to fit the device that it is displayed on. The compatibility with smart phones, iPads, other tablets, and Chromebooks make it a perfect tool for use in a 1:1 classroom.

### Teaching Ideas and Suggestions:

This Interactive can be used during just about any stage of a learning cycle on momentum conservation. There are two distinct outcomes from the use of this Interactive. First, in an explosion (such as the one portrayed by the Interactive), the total system momentum is the same before the explosion as after the explosion. Before the explosion, the system of two carts has zero momentum. After the explosion, there is still zero momentum in the system. The red cart has equal momentum as the blue cart, but directed in the opposite direction. When the two momenta vectors are combined, the result is zero. The second concept to be emphasized is that the actual post-explosion velocities are dependent upon object mass. Since both objects must have equal momentum values, the cart with the smaller mass must have the larger post-explosion velocity. The accompanying activity sheet may be quite useful in highlighting these two ideas. View Activity Sheet.

The Interactive could be used as an open-ended student exploration, a teacher demonstration, or a guided activity. An open-ended student exploration could center around a question as simple as one or more of the following:

• Use the Exploding Carts Interactive to explore the relationship between the pre-explosion momentum of a system of two carts and the post-explosion momentum of the same system of two carts. How are these two quantities related? Collect some data, make a claim as to the relationship, and support the claim with a reference to your evidence (i.e., supporting data) and a discussion of the reasoning as to how the evidence support the claim.

• Use the Exploding Carts Interactive to explore the relationship between the velocities of the two exploding carts of varying mass. Collect some data for different sets of cart masses and organize it in a table. Analyze the data in order to develop a formula that expresses the post-explosion velocity of the red cart (vred) as a function of the blue carts velocity (vblue) and the two cart masses (mred and mblue). Make a claim (the stated formula) and support the claim with a reference to your evidence (i.e., supporting data) and a discussion of the reasoning as to how the evidence support the claim.

See the provided activity for an example of a guided exploration. View Activity.

Our Exploding Carts simulation is now available with a Concept Checker. Do the simulation with the accompanying Activity Sheet. Then follow it up with a Concept Checker.

### Related Resources

There are numerous resources at The Physics Classroom website that serve as very complementary supports for the Exploding Carts Interactive. These include:
• Minds On Physics Internet Modules:
The Minds On Physics Internet Modules include a collection of interactive questioning modules that help learners assess their understanding of physics concepts and solidify those understandings by answering questions that require higher-order thinking. Assignments MC5 and MC6 of the Momentum and Collisions module provide great complements to this Interactive. They are best used in the middle to later stages of the learning cycle. Visit the Minds On Physics Internet Modules.

• Curriculum/Practice: Several Concept Development worksheets at the Curriculum Corner will be very useful in assisting students in cultivating their understanding, most notably ...

Action-Reaction and Momentum Conservation

Visit the Curriculum Corner.

• 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. Two notable lab ideas include ...

Before and After Lab
What's Cooking? Lab

Visit The Laboratory.

• Science Reasoning Activities:
Science classrooms should be filled with reasoning activities. There is one related activity in the Momentum and Collisions section of the Science Reasoning Center that will challenge students to employ close reading, data analysis, and logical reasoning. The activity is named ...

Collisions

Visit the Science Reasoning Center.

Additional resources and ideas for incorporating Exploding Carts into an instructional unit on momentum conservation can be found at the Teacher Toolkits section of The Physics Classroom website.  Visit Teacher Toolkits.

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