Calculating Maximum Speed on Banked Curve: Centripetal Force

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The discussion focuses on calculating the maximum speed a car can take on a banked curve without skidding, given specific parameters such as the curve's radius, banking angle, car mass, and friction coefficient. The user attempted to derive the speed using equations for normal and frictional forces but encountered difficulties in obtaining the correct answer. Other participants pointed out errors in the user's approach, particularly in equating normal and frictional forces and mixing acceleration with force in the equations. A request for a free body diagram was made to clarify the forces acting on the car. The conversation emphasizes the importance of correctly applying physics principles to solve the problem.
swimstar
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A highway curves to the left with radius of
curvature R = 46 m. The highway’s surface
is banked at θ = 26 so that the cars can take
this curve at higher speeds.
Consider a car of mass 1018 kg whose
tires have static friction coefficient µ = 0.57
against the pavement.
The acceleration of gravity is 9.8 m/s/s.

Ho fast can the car take this curve without skidding to the outside of the curve?
Answer in units of m/s.

Here is a link for the picture: https://quest.cns.utexas.edu/student/assignments/problem_pdf?courseuserassignment=10797960

It is question #4.

I tried to do this by setting the equations for Normal Force and Frictional Force equal and solving for V.
Therefore I got,

{ (v2/R)cos(theta) - mgsin(theta) } = { u (v2/R)*sin(theta) + mgsin (theta))

However, I am unable to get the correct answer.

Help is needed as soon as possible. Thank you.
 
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swimstar said:
A highway curves to the left with radius of
curvature R = 46 m. The highway’s surface
is banked at θ = 26 so that the cars can take
this curve at higher speeds.
Consider a car of mass 1018 kg whose
tires have static friction coefficient µ = 0.57
against the pavement.
The acceleration of gravity is 9.8 m/s/s.

Ho fast can the car take this curve without skidding to the outside of the curve?
Answer in units of m/s.

Here is a link for the picture: https://quest.cns.utexas.edu/student/assignments/problem_pdf?courseuserassignment=10797960

It is question #4.

I tried to do this by setting the equations for Normal Force and Frictional Force equal and solving for V.
Therefore I got,

{ (v2/R)cos(theta) - mgsin(theta) } = { u (v2/R)*sin(theta) + mgsin (theta))

However, I am unable to get the correct answer.

Help is needed as soon as possible. Thank you.


The diagram to not show up.

Is it possible for you to draw a free body diagram showing the forces on the car so we might be able to work through the equations you will need based on the diagram?
 
The link asks for a login.
 
swimstar said:
I tried to do this by setting the equations for Normal Force and Frictional Force equal and solving for V.
Therefore I got,

{ (v2/R)cos(theta) - mgsin(theta) } = { u (v2/R)*sin(theta) + mgsin (theta))

.

Why should be the normal force equal to the frictional force?
You mix acceleration and force in your equation. How did you get it?

ehild
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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