What factor significantly affects a roller coaster's speed?

The angle of the first drop is a critical factor that significantly affects a roller coaster's speed due to the principles of physics, specifically gravity and acceleration. When a roller coaster begins its ride with a steep drop, it increases the potential energy of the train at the top of the hill. As the roller coaster descends, this potential energy is converted into kinetic energy, which translates into speed. A steeper angle leads to a faster initial descent, allowing the coaster to gain more speed compared to shallower drops.

The design of the first drop is intentionally crafted by engineers to enhance excitement and maximize speed as the train moves through the rest of the coaster's layout. The other factors mentioned, such as the color of the coaster, do not influence speed, and while the type of train and the length of the track can play roles in the overall experience and dynamics, the initial angle of the first drop is fundamental in determining how fast the coaster will travel right from the start.