Figure 1: Wall fo Death. Taken from https://wheelsthroughtime.com/american-motor-drome-company-wall-of-death-thrillshow/                   

The "Wall of Death," also known as the motordrome, silodrome, or well of death, is a highly popular stunt and often considered a must-master skill for daredevils. It typically involves riding a motorcycle inside a cylindrical, silo-like structure, ranging from 20 to 36 feet (6.1 to 11.0 m) in diameter. While many of us have seen this stunt in movies, it's fascinating to consider the science behind it. Is it all about skill? Yes, but there's also a key physics concept at play here—uniform circular motion.

When a motorcycle rides on the wall, several forces are at work. These include gravitational force (which pulls the bike downward), the frictional force exerted by the wall against the tires, and the normal reaction force, which pushes back perpendicular to the wall's surface. There's also the centripetal force, which pulls the bike toward the center of the circular path.

For the motorcycle to stay on the wall, the normal reaction force is crucial in providing the necessary force to maintain circular motion. The fact that the bike doesn't slide down shows that the frictional force and gravitational force are balanced. However, the frictional force on the tires depends on the bike's speed, so the rider must maintain a minimum velocity to generate enough friction to counteract gravity. If the speed is too low, gravity will win, and the bike will slide down. But speeding up too much makes steering difficult and risky.

The situation becomes more complicated because the forces act on different points. In this case, the gravitational force acts on the center of mass of the bike and rider, while the frictional force is applied through the tires. For the bike to remain on the wall without falling, the rider must position themselves carefully. The rider must lean away from the wall at an angle to prevent the bike from rotating and to counteract any torque (the force that causes rotation). If the rider leans at the wrong angle, the resulting unbalanced torque could cause the bike to rotate and fall.

Thus, leaning at the correct angle is the secret to maintaining balance and ensuring the rider's safety during this dangerous stunt. The physics of torque and the balance of forces are key to making sure these daredevils stay upright on the Wall of Death.

Authors: Mizan Bin Mazzan,Nur Aimi Yusreen Binti Mohd Yusri, Nurul Huda Fatihah Binti Mohamed Kamil, Emma Ziezie Binti Mohd Tarmizi

Date of Input: 01/02/2025 | Updated: 01/02/2025 | emma