Projectile motion experimental vs theoretical results

In summary, the conversation discusses how the experimental results in projectile motion can differ from theoretical results due to factors such as wind resistance and other forces. It is noted that simplified models may not accurately represent real-life situations, and that a more precise model may be needed to accurately predict outcomes. The importance of considering all factors and making clear and complete descriptions in experiments is emphasized.
  • #1
stupif
99
1
in projectile motion, why the experimental results are different with theoretical result?
thank you
 
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  • #2
stupif said:
in projectile motion, why the experimental results are different with theoretical result?
thank you

Things like wind resistance effect real results.

You typically have to study the medium that objects are embedded in. The theoretical models are based on the assumption that the only force acting on the object is gravity, and based on this, the projectile motion equations are derived.

Usually the next step up is to consider something like drag or a co-effecient for wind resistance.

Just as a note for future learning, its a good idea to look at the assumptions used. They might be too few (like introductory projectile motion), or too many (like a model that takes into account fluid dynamics like navier stokes). Sometimes you need to be precise and the "too many" model is sometimes "not enough".

If you wanted to do the most accurate model you would identify all the types of forces and simulate them at a desired level. The math is going to be more complex, but its usually going to be more reflective of what happens.
 
  • #3
but i use steel ball as projectile...the wind will affect the result??or other factors except wind...
 
  • #4
stupif said:
but i use steel ball as projectile...the wind will affect the result??or other factors except wind...

I'm not a physicist, so the short is answer I'm not sure. Can you describe your experiment? Since you mention your using a steel ball, you probably didn't throw it (correct me otherwise).

This is basically what happens in science. You do experiments and find that simplified models don't work, so you either accept their limited accuracy or you add to your model.

Asides from obvious things like wind and drag, I can't off the top of my head think of simple attributes that could be added to your model, without resorting to a first principles approach.
 
  • #5
stupif said:
but i use steel ball as projectile...the wind will affect the result??or other factors except wind...

The wind will definitely affect the result.
 
  • #6
You really need to quantify things in your questions. If you throw a steel ball of 1" radius straight up in the air as hard as you can with no wind, it is going to go straight up and come straight down. If the wind is 100mp the ball is NOT going to go straight up and straight down. A more intelligent question would be, if I throw the ball of radius x, with velocity y, and there is a wind of velocity v perpendicular to the flight path, would the wind affect the ball's landing point by more than z inches?
 
  • #7
stupif said:
in projectile motion, why the experimental results are different with theoretical result?
thank you

It depends on what your theory is. If you have a set up in which the launcher and a penny are at practically the same location, and you theorize the penny will strike the floor first, the experimental result may not support your hypothesis.
 
  • #8
stupif said:
in projectile motion, why the experimental results are different with theoretical result?
thank you

This is VERY vague. What "results" exactly are different? And how much do they differ? If your experimental accuracy is +/- 0.01 and the result differ by 0.001, do you consider this as different? You need to put in SOME effort in present as clear and as complete of a description as possible.

And if this is part of a lab/schoolwork/etc., it should have been posted in the HW/Coursework forum.

Zz.
 

1. What is projectile motion?

Projectile motion refers to the movement of an object through the air under the influence of gravity. This type of motion is a combination of horizontal and vertical motion, resulting in a curved path.

2. How do experimental and theoretical results of projectile motion differ?

Experimental results are obtained through conducting actual experiments, while theoretical results are calculated based on mathematical equations and assumptions. Experimental results may vary due to factors such as air resistance and human error, while theoretical results are based on ideal conditions.

3. Why is it important to compare experimental and theoretical results in projectile motion?

Comparing experimental and theoretical results allows scientists to validate the accuracy of mathematical models and theories. It also helps identify any discrepancies or limitations in the theoretical model.

4. What factors can affect the accuracy of experimental results in projectile motion?

Air resistance, human error in measurement and timing, and external factors such as wind or temperature can all affect the accuracy of experimental results in projectile motion. It is important to control for these factors as much as possible to obtain reliable data.

5. How can we improve the accuracy of experimental results in projectile motion?

To improve the accuracy of experimental results, we can use more precise measuring tools, conduct multiple trials and take an average, and minimize external factors such as air resistance by conducting experiments in a controlled environment. We can also use more sophisticated mathematical models to account for factors that may have been previously overlooked.

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