How Do You Incorporate Drag Force in Free Body Diagrams for Multiple Objects?

  • #1
MeesaWorldWide
7
1
Homework Statement
Three toy ducks on wheels are attached to the same rope and a boy begins pulling one end of the rope with a force of 10 N. The first duck (duck 1) has a mass of 1.0 kg, the middle duck (duck 2) has a mass of 5.0 kg, and the third duck in line (duck 3) has a mass of 2.0 kg. I already calculated the acceleration of the three ducks in part a of this question (1.25 m/s^2). The next thing is to find the tension force in the rope connecting ducks 1 and 2. I don't understand how to go about doing this: any help is appreciated!
Relevant Equations
F = ma
I don't even know how to begin this. I know that I need to somehow account for the drag force that duck 3 is causing on the first 2, but I don't know how to deal with that. I am asking for someone to help me get started, not to give me the answer.
 
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  • #2
There can be shortcuts, but the standard procedure is to draw a free body diagram for each duck and assign unknowns to the forces between them in a consistent manner.
Then write the F=ma equation for each duck.
 
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FAQ: How Do You Incorporate Drag Force in Free Body Diagrams for Multiple Objects?

How do you represent drag force in a free body diagram?

Drag force is typically represented as a vector pointing in the direction opposite to the object's velocity. It is labeled as Fd or Fdrag and is often shown with a magnitude proportional to the square of the object's speed, depending on the drag equation used.

How do you calculate the magnitude of the drag force?

The magnitude of the drag force can be calculated using the drag equation: Fd = 0.5 * Cd * ρ * A * v², where Cd is the drag coefficient, ρ is the fluid density, A is the cross-sectional area, and v is the velocity of the object.

How do you incorporate drag force for multiple objects in a free body diagram?

For multiple objects, each object should have its own free body diagram. The drag force for each object should be calculated based on its individual properties (velocity, cross-sectional area, drag coefficient) and represented as vectors pointing opposite to their respective velocities in the diagrams.

How does the drag force affect the net force in a free body diagram?

The drag force affects the net force by opposing the motion of the object. When summing forces to find the net force, the drag force is subtracted from the other forces acting in the direction of the object's motion. This results in a reduced net force and consequently a lower acceleration according to Newton's second law (F = ma).

How do you handle varying velocities when incorporating drag force in free body diagrams?

If the velocities of the objects change over time, the drag force will also change since it depends on the velocity squared. In such cases, you need to update the drag force continuously or at discrete time intervals, recalculating it based on the current velocity of each object and adjusting the free body diagrams accordingly.

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