STEAMING with STEM: Build a Zipline

Ziplines in America

Many people go on an “Adventure” vacation. One adventure that is popular all over in the United States is ziplining down a mountain, above a body of water, or over a gorge. A zipline is a way to glide from one point to another while hanging from a cable. See what are the most death-defying Ziplines in the U.S.A.

1. CAMELBACK MOUNTAIN ADVENTURES, CAMELBACK MOUNTAIN, PENNSYLVANIA

Ride by chairlift to the top of Camelback Mountain, and be let loose at the top of this 4,000 foot long zipline cable – a length that the company says makes these the longest Zip-Flyers in North America. You’ll reach speeds up to 60 miles per hour as you take in views of the mountain and travel over the Camel beach Mountain Waterpark.

2. CAPTAIN ZIPLINE, SALIDA, COLORADO

Not known for their length, the Captain Zipline tours in Colorado are known for their adrenaline-inducing effects. There are seven lines in total, running up to 700 feet. They reach 40 miles per hour over rugged landscapes of the Arkansas River canyon. You’ll pass mining ruins and looming Rocky Mountain peaks.

3. ICY STRAIGHT POINT, ALASKA, UNITED STATES

The zip in Hoonah Icy Straight Point, Alaska takes 90 seconds to complete a 1,300-foot vertical drop at 24 degrees.

4. The KAPOHINE HAWAII, UNITED STATES

The Kapohine Offers views of the Umauma falls and zips 160′ above 14 other falls.

5. MEGA ZIPLINE HARPERS FERRY, WEST VIRGINIA, UNITED STATES

This ride really makes you feel like you’re flying. You’ll lay in the harness “Superman style.” The Mega Zip Line is 2,100 feet long and pretty snappy at 50 mph.

Build a Zipline

Engineering Connections

Have you ever ridden on a zipline? Ziplines are usually made of a cable that is stretched between two trees or posts. The person riding it wears a harness that is attached to the cable with a pulley that rolls along the line. Ziplines were originally for people to travel in and through wild places such as forests or jungles. Over time, they have become a way for biologists to study the environment. They have also become huge tourist attractions for thrill seekers who want to “zip” through or above the trees. Ziplines are sloped so that the force of gravity pulls the rider down the cable. When designing zip lines, engineers must ensure the safety of riders by considering the weight that the line can support, the speed of the person “zipping” down the line, and the strength of the materials used for both the cable and the harness. Since most modern-day zip lines are designed for fun and excitement, engineers must also balance the need for safety with the desire for a fast, thrilling ride.

Science Connections

Engineers must have a strong understanding of many scientific laws. To design the best solution to a problem, they must know how their design will function in the real world. To build a zip line that is safe for riders, engineers must make sure that it will not only hold a rider’s weight when that rider is on it, but also allow the rider to safely stop before reaching the end. For riders to stop at the end of the zip line, they need to use the force of friction, which is the same force that you use if you drag your feet to stop your bicycle. By pushing two surfaces together, like taking your feet off the pedals and dragging them on the ground, the force of friction increases. The brakes on the zip line also cause a friction force to grow bigger the harder you squeeze. This causes the zipline rider to slow down before the end of the cable. Science and engineering must be used hand-in-hand to make our world useful, safe, and fun.

Design Challenge: ZIPLINE INC want to build a ZIPLINE in Delaware. They want it to be one of the largest in the nation. However, they know it will be a challenge due to Delaware’s low elevation. That want you to build a prototype device that can transport a ping-pong ball from the top of a zip line to the bottom in 4 seconds or less. Remember there should be difference in height between starting and ending points, and the safety needs of a rider. Making zip-lining safe is of critical importance.

Materials

• 1 spool of fishing line or string
• Pairs of scissors
• Hole punches
• Stopwatches
• Several rolls of masking tape
• 100 paper clips
• 1 ping-pong ball
• 4 flat, 1″ steel washers
• 4 index cards
• 4 wooden skewers
• 4 paper cups, 3 oz. size
• 4 straws

Getting Ready

Cut about 4 feet of fishing line to make a zip line. Attach one end of the line to a wall or chair and the other end to an object about 2 feet lower. Make as many zip lines as you want or have space for.

Introduction

Think about it!

Children in the small village of Los Pinos, Colombia, don’t have a school of their own. Instead, they ride a zipline half a mile across a canyon to attend school in a neighboring town.  When designing zip lines, engineers must consider speed;

• What forces are involved in an object moving down a zip line?
• How are zip lines used today?
• What else could they be used for?

Instructions

Introduce the design challenge and provide instructions to the participants: build a device that will transport a ping-pong ball down a zip line from start to finish in 4 seconds or less. Provide the following guidance:

1. Design, build, and test the device.
2. Make adjustments to the weight, center of mass, and friction of the device as needed. Participants may need help assessing what needs to be changed. Ask questions like “What can you do to make your zip line faster?” or “Which materials can help your zip line slide quickly?”
3. Try different prototypes until the conditions of the design challenge are met.

   Evaluate the success of each design.

   Did the designed device carry the ball to the end of the line?

   Did the ball reach the end of the zip line in 4 seconds or less?

    

   Troubleshooting

   If the zip line is too slow, try reducing the friction between the carrier and the line. Also, make sure there is enough of a vertical drop. If the ball falls out of the designed carrier, consider building a larger contraption. Moving the center of mass by placing metal washers at different locations can impact the zip line.

    

   Challenge Yourself

   Raise the stakes by transporting eggs instead of ping-pong balls. Design a way to slow the egg so that it doesn’t crack at the end of the ride. Make several identical long zip lines and have a race.  Design a zip line that can drop the ball onto a target at the end of the ride. Try a zip line that is two or three times as long but keep the 4-second time limit.

    

   After The Activity Questions

   What material(s) did you use to carry your ping-pong ball down the zip line?

   How high were the start and end points of your zip line? Why does this matter?

   Were you able to get your ping-pong ball from the top to the bottom of your zip line in 4 seconds on the first try? What changes did you make after the first test to increase the speed of the ball on the zip line? What factors affect the speed of the ping-pong ball?