Acceleration is the pace at which the speed or direction changes. Some amusement park attractions, such as roller coasters, include abrupt changes in speed and/or direction. These rides feature a lot of acceleration. An example of acceleration is the speed increase of a roller coaster.
Other types of rides that feature acceleration are spinning rides (e.g., The Cyclone), swing sets (e.g., Tarzan's Treehouse), and teacups (e.g., Teacup Tails). Acceleration can also be used to describe the rate at which gravity pulls objects toward the ground. For example, when accelerating upward through the air, you are increasing the rate at which gravity takes away your weight so that it becomes easier to climb higher. This is called "geometric progression." When describing the motion of objects other than people, acceleration usually refers to the rate of change of velocity with time. For example, an object in free fall from a height will accelerate downward at a constant rate because its velocity changes but not its mass per second.
In physics, acceleration is defined as the rate at which the force acting on an object increases. If we consider a person riding in a cart, then the person is applying force to the cart in order to make it go. This applied force causes the cart to accelerate forward. In general, forces cause objects to accelerate.
The majority of amusement park attractions need acceleration. The force of gravity tugging a roller coaster downward leads it to travel faster and faster; it accelerates. When a roller coaster climbs a slope, the force of gravity forces it to go slower and slower. When the roller coaster slows down, it travels slower. All attractions need deceleration too. Just as when you step on the gas or brake pedal in your car, most rides use motors to provide this action.
Some rides also need to be slowed down or stopped completely. This is usually because of what is called "the rule of gravity" which means that if an object is weighty enough, it will fall under its own power eventually. For example, if you were to put a heavy book on top of your head, it would fall off eventually due to the law of gravity. This is why buses and trains need to have their speed reduced occasionally so they do not run into obstacles in the road or tunnel.
The speed at which a roller coaster moves through the air or water is called its "cruise speed". At any given moment, only part of the ride is moving at cruise speed; the rest of it is accelerating or decelerating. For example, if a roller coaster's track was flat, it would never stop speeding up until it reached high speeds or fell over. But since we know that curves are used to prevent this, some parts of the ride must slow down while others keep going.
Gravity pulls you down at every point during a roller coaster ride. Acceleration is the other factor at work on you. That is, until another force acts on you to modify your speed or direction, your body will continue to move at the same speed and in the same direction. The net effect of these two forces is that gravity pulls you down, and acceleration pushes you forward.
As long as you are moving at a constant speed, then the direction of gravity's pull does not matter. It is acceleration that determines whether you are rising up toward the sky or falling back towards Earth. During a roller coaster plunge, you experience both forces simultaneously; thus, the direction of gravity's force changes while you are plunging.
When you reach the top of the plunge, then the force of gravity is pulling you down again. However, because of your acceleration up at the start of the plunge, it appears as if gravity's force was pulling you up at that moment too. Your body is always in motion, so there will be times when gravity's force will be pulling you one way and another force will be acting on you in another direction. That is why it is important to distinguish between acceleration and gravity when using information from a roller coaster.
In conclusion, the direction of gravity's force changes while you are plunging on a roller coaster but returns to its original direction after the plunge is over.