Question on coriolis effect with drag force

In summary, the conversation discusses an object moving on the surface of a liquid at a certain latitude and the forces that affect its trajectory. The drag force is influenced by a constant coefficient, α, which relates to the velocity of the object. The Coriolis force is perpendicular to the speed and does not affect the drag force. The equation for the drag force may vary depending on factors such as density, coefficient of drag, wetted area, and velocity. The conversation also mentions the possibility of the problem being on a planet with different conditions that affect the drag force.
  • #1
ystch
1
0
I really need help with this question.

A small floating object initially moves with velocity v on the surface of a liquid at latitude λ. The drag force due to liquid is F=-αv. Find the shape of the trajectory of the object due to drag and Coriolis forces. What will be the trajectory if α=0 ?
 
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  • #2
What is "α"?
 
  • #3
a would be a constant coefficient in this equation that relates drag force as a function of velocity.

the equation is of similar from as friction where F = u N.
 
  • #4
The coriolis force is perpendicular to the speed, so the drag isn't influenced by the angle that the object is moving. You can solve a differential equation for the maginuted of the speed first: x'' = -ax'
 
  • #5
256bits said:
a would be a constant coefficient in this equation that relates drag force as a function of velocity.

the equation is of similar from as friction where F = u N.

Then α has to be 1/2*ρ*Cd*S*u where ρ=density, Cd=coefficient of drag, S=the wetted area and u the velocity because drag is a function of the square of the velocity.

willem2 said:
The coriolis force is perpendicular to the speed, so the drag isn't influenced by the angle that the object is moving. You can solve a differential equation for the maginuted of the speed first: x'' = -ax'

The drag is indeed influenced by the angle that the object is moving. If it sideslips drag is higher than if it was moving with 0 angle from the longitudinal axis.


ystch,
If I were you, I would perform the kinematic analysis. Consider all forces acting on the object and take under consideration Earth's rotation as well.
α=0 means probably that you ignore the drag so you do the analysis once more neglecting drag.
 
  • #6
Then α has to be 1/2*ρ*Cd*S*u where ρ=density, Cd=coefficient of drag, S=the wetted area and u the velocity because drag is a function of the square of the velocity.

The equation for the problem does not say that.
It says that the drag force has a direct relationship with velocity ( not velocity squared ).
 
  • #7
256bits said:
The equation for the problem does not say that.
It says that the drag force has a direct relationship with velocity ( not velocity squared ).

I know. That's why I say that the equation given is wrong, unless the problem is not on Earth but somewhere else that drad could depend on the velocity and not on the square of the velocity ;) Under this assumption, he can proceed the solving procedure with the given equation.
 
  • #8
Aero_UoP said:
I know. That's why I say that the equation given is wrong, unless the problem is not on Earth but somewhere else that drad could depend on the velocity and not on the square of the velocity ;) Under this assumption, he can proceed the solving procedure with the given equation.

Or it's on earth, in a flow condition dominated by viscous rather than inertial forces (a flow with a very low reynolds number).
 
  • #9
cjl said:
Or it's on earth, in a flow condition dominated by viscous rather than inertial forces (a flow with a very low reynolds number).

Creeping flow... you're right, it slipped my mind.
I haven't dealt with such a flow for like a century :p lol
 

Related to Question on coriolis effect with drag force

1. What is the Coriolis effect?

The Coriolis effect is a phenomenon that describes the deflection of objects or fluids moving in a straight path due to the rotation of the Earth. This effect is caused by the Earth's rotation and is strongest at the poles and weakest at the equator.

2. How does the Coriolis effect impact weather patterns?

The Coriolis effect plays a significant role in shaping global weather patterns. In the Northern Hemisphere, winds are deflected to the right, and in the Southern Hemisphere, they are deflected to the left. This deflection creates the distinct wind patterns and circulation systems that we see on Earth.

3. What is the relationship between the Coriolis effect and the drag force?

The drag force is a force that opposes the motion of an object through a fluid. In the context of the Coriolis effect, when an object or fluid is moving on the surface of the Earth, the Coriolis effect can combine with the drag force to create a circular motion. This is known as a geostrophic flow.

4. How does the Coriolis effect impact ocean currents?

The Coriolis effect also plays a crucial role in shaping ocean currents. Just like in the atmosphere, the Coriolis effect deflects ocean currents to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. This creates the circular motion of ocean currents and contributes to the distribution of heat and nutrients in the ocean.

5. Is the Coriolis effect the same everywhere on Earth?

No, the strength of the Coriolis effect varies depending on the latitude. It is strongest at the poles and weakest at the equator. Additionally, the Coriolis effect is also affected by the speed of the object or fluid and the distance it travels. This means that the Coriolis effect can vary in different regions of the Earth and for different objects or fluids.

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