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Zip Line Physics


Curt Blimline

Unit Title:

Zip Line Physics





Estimated Duration:

9 60 min periods

Unit Activities:

Background Knowledge: 

Students should have a working knowledge of Newton’s laws of motion and a basic understanding of vectors in physics. Students should also have a basic understanding of the algebra, geometry and trigonometry, particularly as it relates to triangles.


June 2013

The Big Idea (including global relevance)

Human Safety

Zip lines have been used for many years to transport goods and individuals across remotely accessible terrain. In recent years, zip lines have become popular as entertainment rides in vacation destinations. The engineering and design of both safe and enjoyable zip line rides is an important consideration for these businesses as they cater to individuals that are not experienced in the use of zip lines. Many countries depend upon a vibrant tourism industry as part of their economic base. Having safe and enjoyable attractions contribute to the viability of the tourism industry. Upon completing this unit, students will have a better understanding of the physics and engineering principles involved in zip lines and the tasks mechanical, structural, and material engineers face in making them safe as well as enjoyable for riders.

The Essential Question

What factors contribute to the safety and enjoyment of zip line rides?
Justification for Selection of Content

Zip lines have been around for many years but have been popularized in recent years for entertainment purposes. Because of the current interest in these attractions, students are more likely to be engaged in activities exploring their function and design. This provides the vehicle to explore and learn physics and engineering concepts required as part of the Ohio and National Standards in physics.

The Challenge

Design a zip ride trolley system with a braking mechanism that delivers a safe and smooth ride on a test zip line.

Teacher's Guiding Questions

1.      What are the components of a zip line system?

2.      What are zip lines used for?

3.      What design characteristics contribute to the smoothness of the ride?

4.      How do you brake a zip line trolley?

5.      How do you determine the safety of your design?

ACS (Real world applications; career connections; societal impact)

A (real world Application) – In this unit, students will investigate zip line systems. Safety of these systems is important for the safe transport of individuals and goods. Using the knowledge gained from the activities in this unit involving forces, students will use the engineering design process to design a safe zip line trolley system using various constraints.

C (career connections) – Careers impacted by this unit will include mechanical, structural, and materials engineering. By completing this unit, students will better understand the role that mechanical engineers (component design), structural engineers (zip line run or course design), and material engineers (product materials), play in ensuring the enjoyment and safety of zip line systems.

S (societal impact) – Each activity in this unit allows the student to explore some of the physics involved in designing zip line systems that can help make their use safe for our society. Safe zip line systems allow goods and individuals to reach remote areas not easily accessible by other transportation. Zip lines used for entertainment or accessibility to nature enhances human enjoyment and relaxation.

Engineering Design Process

The engineering design process is introduced in Activity 1 as students in teams work through the engineering design process to design and construct a zip line structure that will deliver a ball into a cargo box. They must document each step of the EDP through an EDP documentation table. The culminating activity of this unit involves students in teams designing and building a working zip line trolley system that emphasizes and incorporates safety features as well as an automatic braking system. All steps of the EDP are required and student teams will present their products and documentation of the EDP through a PowerPoint presentation to students, faculty, administrators, and community and business members.

Unit Academic Standards


  1. Air Resistance and Drag
  2. Friction
  3. Forces in two dimensions
            a. Adding vector forces
            b. Motion down inclines


HS-PS2-1. Analyze data to support the claim that Newton’s second law of motion describes the mathematical relationship among the net force on a macroscopic object, its mass, and its acceleration.

HS-ETS1-2. Design a solution to a complex real-world problem by breaking it down into smaller, more manageable problems that can be solved through engineering.

HS-ETS1-3. Evaluate a solution to a complex real-world problem based on prioritized criteria and trade-offs that account for a range of constraints, including cost, safety, reliability, and aesthetics as well as possible social, cultural, and environmental impacts.

Where the CBL and EDP appear in the Unit
CBL and EDP are used in Activities 1 and 4.
  1. Forces are required for motion with constant velocity.
  2. All objects can be moved with equal ease in the absence of gravity.
  3. All objects eventually stop moving when the force is removed.
  4. Inertia is the force that keeps objects in motion.
  5. Action-reaction forces act on the same body.
  6. There is no connection between Newton’s laws and kinematics.
  7. The product of mass and acceleration is a force.

Additional Resources

Websites for research:

Pre-Unit Assessment Instrument
Post-Unit Assessment Instrument
Results: Evidence of Growth in Student Learning

After teaching the Unit, present the evidence below that growth in learning was measured through one of the instruments identified above. Show results of assessment data that prove growth in learning occurred.

The gain from a 16% to 77% average pre to post assessments as well as gains in subgroups demonstrates the impact on student learning. Also, most student comments were positive about their learning experiences.


Most everything went smoothly and I wouldn’t make many changes to the unit. I will use all four activities again for this unit. I might possibly add an activity on free body diagrams to complement acitivity 2 as that was the only area on the post-assessment that some students didn’t get completely correct.