Nonconservative Forces Problem with a Model Airplane

In summary: I'll critique it.In summary, the model airplane decreases its speed from 14 m/s to 8 m/s, and does work to do so.
  • #1
momoneedsphysicshelp
23
2
Homework Statement
A model plane of mass 5.3 kg moves from a height of 15 m to a height of 17 m while decreasing its speed from 14 m/s to 8 m/s. How much work is done by non-conservative forces acting on the plane?
Relevant Equations
—350 J
+104 J
—88 J
—245.9 J
+350 J
—104 J
+88 J
+245.9J
—15.9 J
+15.9 J
I am sure that the answer will be negative, but I'm not 100% sure on how to solve the problem. My initial answer was -350 J. Please help. Thanks!
 
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  • #2
momoneedsphysicshelp said:
Homework Statement:: A model plane of mass 5.3 kg moves from a height of 15 m to a height of 17 m while decreasing its speed from 14 m/s to 8 m/s. How much work is done by non-conservative forces acting on the plane?
Relevant Equations:: —350 J
+104 J
—88 J
—245.9 J
+350 J
—104 J
+88 J
+245.9J
—15.9 J
+15.9 J

My initial answer was -350 J.
I assume those "Relevant Equations" are the options.
(That section of the template is for standard physics equations, like F=ma.)
Please post your working.
 
Last edited:
  • #3
momoneedsphysicshelp said:
Homework Statement:: A model plane of mass 5.3 kg moves from a height of 15 m to a height of 17 m while decreasing its speed from 14 m/s to 8 m/s. How much work is done by non-conservative forces acting on the plane?
... I am sure that the answer will be negative, but I'm not 100% sure on how to solve the problem. My initial answer was -350 J. Please help. Thanks!
This problem seems to be confusing to me, unless we assume that the model airplane does not have a thrust force acting on it.
A powerful engine would constantly supply mechanical energy to the airplane, which would need to be accounted for in the solution of the problem.
Let's assume the model is a glider instead.

If so, it is not different from a problem showing a ball rolling on an inclined plane and increasing is height respect to the ground.
Initial kinetic energy is used to increase potential energy and to overcome frictionor aerodynamic drag in the case of the airplane.

https://www.grc.nasa.gov/www/k-12/airplane/smotion.html

smotion.gif
 
  • #4
Lnewqban said:
This problem seems to be confusing to me, unless we assume that the model airplane does not have a thrust force acting on it.
The thrust, if present, will be one of the nonconservative forces ! If you are confused, why try to answer the question?

For the OP consider conservation of energy. Show how you got your answer (I'm not going to do it as per our suggested rules)
 

1. What are nonconservative forces and how do they affect a model airplane?

Nonconservative forces are external forces that cause a change in the mechanical energy of a system. In the case of a model airplane, these forces can include air resistance, friction, and gravity. These forces can cause the airplane to slow down or deviate from its intended path.

2. How can I account for nonconservative forces in my model airplane design?

To account for nonconservative forces in your model airplane design, you can use mathematical models and simulations to estimate the effects of these forces on the airplane's flight. Additionally, you can make design adjustments such as reducing the weight of the airplane or using aerodynamic shapes to minimize air resistance.

3. How do nonconservative forces impact the flight performance of a model airplane?

Nonconservative forces can significantly impact the flight performance of a model airplane. These forces can cause the airplane to lose altitude, decrease speed, and decrease stability. They can also affect the overall flight time and distance of the airplane.

4. How can I minimize the effects of nonconservative forces on my model airplane?

To minimize the effects of nonconservative forces on your model airplane, you can use techniques such as streamlining the design, using lightweight materials, and adjusting the center of gravity. Additionally, you can also adjust the flight path and speed of the airplane to counteract the effects of these forces.

5. Are there any real-life applications for understanding nonconservative forces in model airplanes?

Yes, understanding nonconservative forces in model airplanes can have real-life applications in fields such as aeronautical engineering and aviation. By studying these forces in model airplanes, scientists and engineers can gain insights into how to improve the design and performance of full-scale aircraft.

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