# Newton’s and gravity exerts a force on the car

Newton’s 3 Laws of Motion: Sir Isaac Newton’s three laws of motion describe the relationships between an object in motion and forces that act on it. Newton’s first law of motion known as the Law of Inertia describes an object’s resistance to changes in its velocity. If an object is in motion, it tends to stay in motion unless an external force acts upon it. This is also true for objects at rest tend to stay at rest. The Law of Inertia can be applied to the Boomerang and to the riders. As the coaster car is pulled up the lift hill at the beginning of the ride and is then released, it will have enough energy from the hill to remain in motion through the rest of the ride until the brakes are applied. The car’s inertia and the rider’s inertia wants to maintain a straight direction however, the tracks exert an external force on the car and changes its direction and magnitude. At the end of the roller coaster when the brakes are applied, the riders are thrown forward due to their inertia. The riders have a tendency to continue moving forward but the brakes stop their velocity. Newton’s second law describes the relationship between the mass of an object, its acceleration and the applied force exerted on the object. The relationship can be calculated using the equation: F=ma, where F is the applied force, m is the mass and a is the acceleration. The two primary forces applied on roller coasters are the force of gravity and the force of the track against the car. Frictional force and air resistance also play a minor role in the forces applied to the car. The mass of the car plus the mass of the riders are constant throughout the ride. On the arms of the Boomerang, the car goes down the hill and gravity exerts a force on the car and the riders. This causes the car to accelerate. The equation can be rearranged to isolate for acceleration: a = F/m. The applied force varies at each point of the roller coaster because the acceleration is never constant. Newton’s third law is the Law of Action-Reaction which is that for every action force, there is an equal and opposite reaction force. For instance, when you high-five a friend, you apply a force on your friend’s hand. Your friend’s hand will apply an equal force back at your hand. Due to the riders’ inertia, when the car is accelerating it feels as if there is an applied force in front of the riders however it is actually coming from the seat that is pushing the riders forward. This force is measured in g-forces and is measured in g where 1g is equal to the force of gravity (9.81m/s2). During the down hills of the Boomerang, simultaneously, the force of gravity pulls the car down and the acceleration force give the riders a feeling that they are getting pulled up. When these opposite forces have the same magnitude they cancel out and so no force is acting on the riders. The riders will feel a sensation of weightlessness.