Physics roller coaster question

In summary, the conversation is about solving a physics problem involving the stopping force required for a roller coaster. The force is calculated using the formula F x d= 11172000, and the result is 1596 000 N. However, there are some discrepancies due to the problem not accounting for real-life factors such as friction and air resistance.
  • #1
meso
9
2
Homework Statement
Consider the frictionless roller coaster shown below.( the picture Is attached below)

If a 12 000 kg car starts at rest from Point A, calculate
a) the total energy of the system

b) the speed of the car at point B


c) the force that must be applied to bring it to a stop at point E


d) the work done to bring it to a stop at point E
Relevant Equations
Eg=mgh
Ek=1/2mv^2
W=Fcos0 x d
Etotal= Ek1 + Eg1
W= delta Ek ( Ek2 – Ek1)
I am stuck at C and D. I tried to solve D by applying W= delta E
W= Etotal
F x d= 11172000
F= 11172000/7
But I am not sure if it is right
 

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  • #2
meso said:
I am stuck at C and D. I tried to solve D by applying W= delta E
W= Etotal
F x d= 11172000
F= 11172000/7
But I am not sure if it is right
Looks right.
 
  • #3
The problem is not specific about the deceleration distance, but assuming the whole last 7 meters are used for stopping the 12 000 Kg car, then one needs to solve d) first in order to be able to solve c) in the way you have shown.
That is a huge stopping force.
 
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  • #4
Lnewqban said:
The problem is not specific about the deceleration distance, but assuming the whole last 7 meters are used for stopping the 12 000 Kg car, then one needs to solve d) first in order to be able to solve c) in the way you have shown.
That is a huge stopping force.
I found the force required to stop the roller coaster to be 1596 000 N, but I am not sure neither confident about my solution.
 
  • #5
meso said:
I found the force required to stop the roller coaster to be 1596 000 N, but I am not sure neither confident about my solution.
Your solution is correct. :smile:
It is only that the problem is not very complying with real life.
With no resisting friction or aerodynamic drag, the speed at ground level would be 155 km/h (43.17 m/s in free-fall).
The corresponding deceleration during those 7 meters would be ##-133~m/s^2##, which equals 13.6 G, which would be too much for comfort.
 
Last edited:
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  • #6
Thanks. Also, that makes sense but I am doing physics grade 12, so they disregard some factors for the sake of this course.
 
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FAQ: Physics roller coaster question

1. What is the physics behind a roller coaster?

The physics behind a roller coaster involves the principles of energy, gravity, and motion. The roller coaster car gains potential energy as it is pulled up to the top of the first hill, and then converts that potential energy into kinetic energy as it travels down the hills and through loops. The car's motion is controlled by the forces of gravity and the track design, which keeps the car on the track and allows for thrilling drops and turns.

2. How does a roller coaster stay on the track while going upside down?

A roller coaster stays on the track while going upside down due to the principles of centripetal force and inertia. Centripetal force is the force that keeps an object moving in a circular path, and inertia is the tendency of an object to resist changes in its motion. The track design and the speed of the roller coaster car work together to create enough centripetal force to keep the car on the track while going upside down.

3. What is the role of friction in a roller coaster?

Friction plays a crucial role in a roller coaster by providing the necessary grip between the wheels of the car and the track. Without enough friction, the car would not be able to stay on the track and would slide off. However, too much friction can also slow down the car and make the ride less thrilling. Engineers carefully design the track and wheels to balance the amount of friction needed for a safe and exciting ride.

4. How do roller coasters use potential and kinetic energy?

Roller coasters use potential and kinetic energy to create a thrilling and dynamic ride. The car gains potential energy as it is pulled up to the top of the first hill, and then converts that potential energy into kinetic energy as it travels down the hills and through loops. The car's speed and motion are constantly changing as it moves through the track, transforming between potential and kinetic energy.

5. What safety measures are in place on roller coasters?

Roller coasters have several safety measures in place, including seat belts, lap bars, and over-the-shoulder restraints. These restraints are designed to keep riders securely in their seats and prevent them from falling out. The track and cars are also regularly inspected and maintained to ensure they are in good working condition. Additionally, roller coasters have emergency systems, such as brakes and sensors, that can stop the ride if necessary.

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