Absorb the Shock!

An engineering activity

Key conceptsEngineeringPhysicsDesignVibration

IntroductionHave you ever ridden in a car over a pothole or a speed bump? You might feel the bumps and get tossed up and down in your seat a little bit, but not nearly as much as you would if the car did not have suspension. Try this engineering project to learn how suspension can help give you a smoother ride!

BackgroundYou might not give it much thought if you are riding down a smooth, nicely paved road, but a car's suspension is very important when driving on a bumpy road or over obstacles. It helps protect the car (and the passengers) from damage when the car goes over a big bump. A car's frame is not rigidly connected to the wheels. If it were, every single bump or vibration experienced by the wheels would be transferred directly to the car and the people inside—making for quite an uncomfortable ride. Instead, the wheels are connected to the rest of the car with a combination of springs (metal parts that bounce back to their original positions when stretched or compressed) and dampers (parts that use friction to slow down motion, usually in the form of a piston filled with viscous oil), also called shock absorbers. Combined, these parts help absorb and decrease road vibrations. In this project you will build your own simple model car and design a suspension system to help prevent the cargo (packing peanuts) from being tossed out of the car when it drives over bumps!

MaterialsThis is an engineering design project, meaning there is not an exact list of materials that you must use. The following list is a suggestion, but feel free to substitute other materials.

Preparation

Procedure

Observations and resultsYou should find that when you attach the cardboard box directly to the frame of your car, many of the packing peanuts are tossed out of the box when you pull it over the speed bumps. This occurs because the vibrations from the wheels are transferred directly to the cardboard box. This would be like riding in a car with no suspension—quite an uncomfortable ride! When you add a suspension, it helps absorb some of the vibrations, so the cardboard box does not bounce up and down as much and doesn't toss out as many of the packing peanuts. It might take some tweaking, however, to get your suspension working well. The stiffness (thickness/length/tightness of the rubber bands or springs) and weight of an object (for example, adding coins) have a big impact on how it reacts to vibrations. Real engineers carefully design a car's suspension to optimally absorb vibrations on the road, just like you did in this project!

This project was inspired by the Trash Sliders activity, by Larry Richards, via eGFI.

More to exploreBalloon-Powered Car Challenge, by Science BuddiesSuspended Science: How Does a Hovercraft Hover?, from Scientific AmericanFight Slippage with Friction, from Scientific AmericanScience Activities for All Ages!, from Science Buddies

This activity brought to you in partnership with Science Buddies

Ben Finio is a senior staff scientist at Science Buddies and a lecturer at the Cornell University Sibley School of Mechanical and Aerospace Engineering. Follow him on Twitter @BenFinio.

Lauren J. Young

Luke Taylor and Nature magazine

Chelsea Harvey and E&E News

Tim Vernimmen and Knowable Magazine

Diana Reiss | Opinion

Manon Bischoff