Semi-trailers are composed of two parts: a towing engine and the cargo trailer. Cargo trailers are interchangeable and movable storage units that contain the actual cargo. These units come in many different forms and can be refrigerated, heated or pressurized to protect the cargo inside from the elements. As a science project, students can explore the different methods of treatment for different types of cargo. They can even create their own cargo transport company as an experiment and describe what sort of cargo trailer treatment would be necessary to transport different types of cargo in different environments.
Most semi-trailers use an air compression system for braking. Unlike most cars, which use hydraulics, semi-trailers brake by the gradual release of air built up in the braking system. Students exploring the science behind semi-trailer braking systems can compare the technical properties of both hydraulic and air compression systems. When comparing the two systems, students can understand the science behind different states of matter and how compression affects liquids and gases differently. After researching the braking systems and how they work, students can hypothesize why air compression braking systems are favorable for large vehicles, such as semi-trailers.
Semi-trailers, like cars, emit large amounts of carbon dioxide into the atmosphere. Carbon dioxide is one greenhouse gas associated with global warming. One project associated with semi-trailers allows children to understand the science and chemistry behind carbon dioxide emissions and why it is harmful to the environment. Using various sources, students can calculate how much carbon dioxide semi-trailers emit into the air per day and determine how much damage this causes to the ozone daily. Additionally, semi-trailers emit a fine diesel dust which has been associated with higher cancer rates.
The transmissions of all vehicles are run by gears. Gears are one type of simple machines that when put together form a complex machine that change the transmission of trucks. Most semi-trailers use a manual transmission which allows the driver to have more control over the truck when it's going up and down hills. Students can do science projects based on how gears work to control the transmission and why most semi-trailers use a manual transmission for greater control. They can also explore the physics behind daily truck operations -- such as speed and momentum -- when examining gears.