Question

The Tornado is a carnival ride that consists of vertical cylinder that rotates rapidly aboat its vertical axis. As the Tornado rotates, the riders are presscd against the inside wall of the cylinder by the rotation, and the floon of the cylinder drops away. The force that points upward. preventing the riders from falling downward, is a) friction force c) gravity. b) a normal force. d) a tension force.

Short answer

Answer: b) A normal force

Step-by-step solution

Understand the forces acting on the riders

In this scenario, as the Tornado rotates, the riders are subjected to different forces. The force acting towards the center of the cylinder is centripetal force, which causes the riders to be pressed against the inside wall. As the floor drops away, another force is required to prevent the riders from falling downwards.

Analyze the given options

Now, let's go through each option and analyze if it can be the force that prevents the riders from falling downwards: a) Friction force The friction force acts between the riders and the inside wall of the cylinder. This force is usually parallel to the surfaces in contact and it opposes the relative motion. In this case, friction force can support the riders moving in the circular path, but it cannot provide the upward force needed to prevent riders from falling. b) A normal force The normal force acts perpendicular to the contact surface between two bodies. In this scenario, the normal force acts between the riders and the inside wall of the cylinder. Since the riders are pressed against the wall, the normal force would indeed be the force that is pointing upward and prevents the riders from falling downward. c) Gravity Gravity is the force that attracts a body towards the center of the Earth. It acts vertically downward on the riders. In this case, gravity is the force trying to pull the riders down, so it cannot be the force preventing them from falling downward. d) A tension force Tension force is the force that is transmitted through a rope, string, chain, or other objects when it's pulled tight by the forces acting from opposite ends. In the Tornado ride, there is no apparent object in tension supporting the riders from falling downward.

Choose the correct answer

From the analysis in Step 2, we can deduce that the correct answer is: b) A normal force. This is because the normal force acts perpendicular to the contact surface (the inside wall of the cylinder) and provides the required upward force to prevent the riders from falling downward as the Tornado ride spins.

Key concepts

Centripetal Force

Imagine you're on a merry-go-round, holding on tightly as you spin around. The force that keeps you moving in a circle instead of flying off is called centripetal force. This force is always directed towards the center of the rotation.

On a carnival ride like the Tornado, riders experiencing this force are pushed against the wall. It's due to this inward force that the riders don't simply float away when the floor drops. Centripetal force, however, doesn't act upwards or downwards; it acts towards the center of the circular path that the riders are on.

It's critical to comprehend that centripetal isn't a type of force itself, but a term for the resultant force that keeps an object moving in a curved path. In the case of carnival rides, this can be a combination of gravitational force, normal force, and sometimes tension force.

Normal Force

When considering what prevents riders on the Tornado from plummeting once the floor recedes, we speak about the normal force.

This is the support force exerted upon an object that is in contact with another stable object; think of a book resting on a table. For the Tornado, the normal force comes into play between the riders and the cylinder's wall. Once riders are spun at sufficient speed, they press against the wall, which pushes back with an equal force perpendicular to the surface -- this is the normal force.

Since the riders are stuck against the wall, the normal force here is acting upwards, opposing the gravitational force, effectively keeping the riders in place and preventing them from falling.

Friction Force

Now, friction force is like the friend that helps you walk across a slippery floor without falling; it resists motion between two surfaces that are in contact.

On the Tornado ride, friction plays a significant role in keeping the riders from sliding down the wall once the ride spins. It acts parallel to the two surfaces in contact – between the riders' backs and the wall of the cylinder – opposing the relative sliding motion of the riders against the wall.

It's worth noting that while friction helps in preventing slipping, it is not responsible for supporting riders against gravity; this job is handled by the normal force, as previously explained. Friction force is crucial in understanding movements where there’s direct contact involved and plays a role in many aspects of physics beyond carnival rides.

Gravitational Force

Last but not least, we have the gravitational force. Often referred to simply as gravity, it's the invisible force that pulls two masses together.

For example, it's what keeps our feet on the ground and causes an apple to fall from a tree. On the Tornado ride, the gravitational force is acting on the riders straight downward towards the Earth's center. This is the same force that would cause the riders to drop if it were not for the upward normal force acting against it.

Understanding gravity is key to not just amusement park rides but in broader phenomena such as planetary orbits, tides, and many fundamental aspects of our daily lives.