Team USA’s four-man bobsledding team is hoping to win their first gold in more than 60 years during the Vancouver Winter Olympics.
Bobsledding got its name in the 1890s in Switzerland because riders bobbed back and forth to increase their speed.
Today’s bobsledders use precision moves and a knowledge of physics to maximize velocity – the speed of the bobsled as it races downhill.
Acceleration is the increasing of the bobsled’s velocity. It begins during the 50-meter start when the team’s feet push against the ice to pick up speed. The team gets the bobsled moving by pushing the sled with maximum force.
While they are in the push stage, everything the bobsledders do is important. This is the riders’ only chance to apply force. There isn’t a way for them to apply more force once they are in the sled. If they can can go faster by even a tenth of a second at the top of the course, they can maintain an advantage all the way down the track.
Next, the team has to get into the sled while keeping it steady and on a straight trajectory. Allowing the sled to move back and forth creates friction, which will slow it down.
Once they are in the sled, the team members must conserve the force they began with. This is the point where gravity takes its turn to accelerate the sled . Gravity is constant for all sledders, no matter their mass or weight, making that initial push extremely important.
As they rocket down the course, the bobsledders will experience 5G’s or five times the force of gravity. This is similar to what fighter pilots feel.
The sledders will be rocked around inside the sled. They will feel 5Gs to the right, then 5Gs to the left. The force is so strong, if a sledder bends their head forward on a curve, their neck muscles are not strong enough to pull their head upright.
Once inside the sled, the only way sled teams can affect their run time on the course is to minimize the loss of forces that can slow the sled – air resistance or drag and friction.
Everything about a bobsled is designed to reduce drag, from the sleek sled body, to the team’s suits and their formation inside. They want air to flow over the bobsled with minimum resistance.
The riders also try to reduce friction on the sled. Every curve and edge of the course can slow the sled down if it rubs against the sides. If the sled loses the momentum gained during the push, the sled cannot gain that momentum back.
A strong push on the top, then very calculated motions on the way down propels the most successful bobsledders to the podium.
Get more information from NBCOlympics.com and the National Science Foundation. Lesson plan available on Air Drag and Friction Effects on the Bobsled at NBCLearn.com.