Physics 250 Laboratory: Conservation of Energy

Penn State University
Type Category
Assessment Materials
Experiment/Lab Activity
This resource, vetted by NSTA curators, is provided to teachers along with suggested modifications to make it more in line with the vision of the NGSS. While not considered to be "fully aligned," the resources and expert recommendations provide teachers with concrete examples and expert guidance using the EQuIP rubric to adapted existing resources. Read more here.


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This is a lab activity involving transformations between the gravitational potential energy, elastic potential energy, and kinetic energy of a system. An air track with a glider and a photo gate timer are needed to perform the lab. The lab is divided into three separate but related parts. The first part involves using a spring to launch the glider horizontally, measuring the velocity of the glider, and then relating elastic potential energy to kinetic energy. The second activity involves adjusting the air track so that when the glider is launched, it goes up an incline. This set up allows students to relate elastic potential energy to gravitational potential energy. The third and final activity ties elastic potential, gravitational, and kinetic energy together. Using the knowledge they acquired from the first two activities, the students need to use Conservation of Energy to predict the velocity of the glider as it is launched up the incline and then compare their prediction to the experimental value.

Intended Audience

Educational Level
  • Grade 12
Access Restrictions

Free access - The right to view and/or download material without financial, registration, or excessive advertising barriers.

Performance Expectations

HS-PS3-1 Create a computational model to calculate the change in the energy of one component in a system when the change in energy of the other component(s) and energy flows in and out of the system are known.

Clarification Statement: Emphasis is on explaining the meaning of mathematical expressions used in the model.

Assessment Boundary: Assessment is limited to basic algebraic expressions or computations; to systems of two or three components; and to thermal energy, kinetic energy, and/or the energies in gravitational, magnetic, or electric fields.

This resource is explicitly designed to build towards this performance expectation.

Comments about Including the Performance Expectation
This activity gives students the opportunity to use the models of elastic potential, gravitational potential, and kinetic energy as well the law of Conservation of Energy. However, none of the three activities require students to develop their own models. To fully meet the Performance Expectations, this lab needs to require the students to develop their own models. Because this activity does not provide the relevant background knowledge, the instructor will need to preface this lab with a lesson on elastic and gravitation potential energies and the law of Conservation of Energy so that the students can gain a deeper understanding about why those energies are equal in activity two.

Science and Engineering Practices

This resource is explicitly designed to build towards this science and engineering practice.

Comments about Including the Science and Engineering Practice
In the third activity, students use mathematical models to represent various forms of energy and to make predictions about what will happen to the system To fully align with the practice, the students should develop the model and explain why, beyond sources of error, there is a difference between the speed of the glider they predicted and what they measured. The concept of some friction should be taught before performing this experiment so that the students can measure the friction present in the lab and use the work done by friction to help account for the difference in theoretical and experimental speeds.

Disciplinary Core Ideas

This resource is explicitly designed to build towards this disciplinary core idea.

Comments about Including the Disciplinary Core Idea
The activity focuses on how the elastic potential energy of the spring was transferred to the glider where it manifested itself as either kinetic energy or gravitational potential energy. Since the glider is sliding on an air track, friction is minimized, thereby allowing measurements that closely match theory and allowing students to appreciate the validity of the Law of Conservation of Energy.

Crosscutting Concepts

This resource is explicitly designed to build towards this crosscutting concept.

Comments about Including the Crosscutting Concept
The Law of Conservation of Energy is at the root of this activity. Students are required to assume that energy is conserved and that there is no friction to determine the spring constant of a launcher and to predict the velocity of a glider on an air track. The students are to compute the percent error between their theoretical velocity calculations and their empirical data. To better address the idea of conservation of energy Crosscutting Concept, have students explain why measurement error isn’t the only explanation for the difference between the measured velocity and the calculated velocity.

Resource Quality

  • Alignment to the Dimensions of the NGSS: This resource significantly addresses the elements of the Practice, the Disciplinary Core Ideas, and the Crosscutting Concepts. The resource addresses the Practice because the students use mathematics to calculate energies. The Disciplinary Core Idea is addressed because mathematics is used along with the concept of conservation of energy to describe the behavior of the system. The resource addresses the Crosscutting Concepts by making students experiment with the conservation of energy.

  • Instructional Supports: The resource is lacking in a few aspects. The resource would be stronger if it included questions or problems to engage the students in three-dimensional learning and asked the students to connect their explanation of the phenomenon to their own experience.

  • Monitoring Student Progress: While this resource requires numerous responses from the students, but it does not require them to utilize high level thinking skills. It also requires students to analyze data, graph data, and analyze these graphs. All of these aspects aid the teacher in their attempt to monitor student progress, albeit after completion of the activity. However, the last requirement of the activity strongly supports the monitoring of student progress during the activity. As a wrap-up exercise, the students need to use what they learned from the lab to make a prediction. They then must either post their prediction on the board or show their instructor. By having to communicate their predictions before the completion of the lab, the instructor is able to actively monitor the students and offer guidance if needed. To earn a higher rating, this resource should include rubrics, scoring guidelines, and guidance for the teacher to know how to interpret student data.

  • Quality of Technological Interactivity: (The resource is a pdf that describes the activity and has no technological component.)