Physics Laboratory (Projectile Motion)

In summary, the ball is deflected to the left or right when launched at a range of 40 or 50, but it lands in the expected position when launched at 10 or 20. The frictional force may be causing the ball to rotate.
  • #1
Mathoholic!
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0

Homework Statement



I'm doing this experiment in physics laboratory (I) about projectile motion and I'm concerned about some of the results (range) I'm getting. I'm using spherical projectiles about 3.0 cm wide (diameter).

Here's the thing, with the launch angle from 10 to 20 (thus, from 80 to 70) I'm getting everything as the theory predicts.

However, when I launch it at 45 (max range) or even 40/50 I get a maximized range but I get deviations of the balls in the y axis, meaning that |Δy|>0 (and not ≠0 as it should be).

Homework Equations



I've asked my professor and even suggested the cause of it being the aerodynamics of the balls along with the friction force but he denied it and didn't give me a straight fulfilling answer.

The Attempt at a Solution



My 'theory' about these deviations is that the farther a ball travels, the more time it's subjected to the friction force (obvious) and so, along with variations of pressure (due to its movement) the ball is forced to deflect (rotate) to the left or right. Again, I'm not sure this is true.


I could really use some feedback from you guys :-p
 
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  • #2
Do you mean you get deviations in where the ball lands? (I'm assuming that's what you are measuring). You were saying the ball is deflected to the left or right. So that means the ball lands somewhere which is not along the direction it was launched in? And so the 'y axis' is horizontal and perpendicular to the launch direction?
 
  • #3
BruceW said:
Do you mean you get deviations in where the ball lands? (I'm assuming that's what you are measuring). You were saying the ball is deflected to the left or right. So that means the ball lands somewhere which is not along the direction it was launched in? And so the 'y axis' is horizontal and perpendicular to the launch direction?

Exactly and I'm sorry for not being clearer. What do you think?
 
  • #4
I can think of another possible reason that doesn't involve friction. But your explanation sounds reasonable too. I think maybe you need to explain your theory more. You've said the friction force deflects it to the side, and that the longer its in the air, the more this deflection is. So starting with a small deviation in the position, or spin, or whatever of the ball, then in what way does friction act to magnify this, and how does this affect the lateral position of the ball?
 
  • #5
What's your reason not involving friction?

Those deflections lead me to believe that the ball rotates. I don't know what's the dynamics behind it while it's in the air, I mean, I do but not with accurate precision. I imagine that while the projectile is in the air, friction as long with pressure variations play a part by introducing spin onto the ball, just maybe.

Other cause that can explain the desviations may be due to the launcher. Perhaps, when it's initially launched, the launcher gives the ball a small but signficant rotation and as it progresses along its path, it contributes to deflecting from the x axis. The farther it travels, the more it deflects.

What do you say about this one?
 
  • #6
the idea that the frictional force causes the ball to curve to the side is a reasonable explanation. I think maybe your professor said no because there is a simpler and more likely explanation for why Δy is greater when the ball spends more time in the air. For the simpler explanation, imagine there is no air friction, and the ball doesn't spin, and there's no air pressure differences. So now we can think of the motion of the ball depending on only the initial velocity of the ball when it is launched. So if there is some slight deviation in the direction the ball was launched, then how will this affect the motion of the ball afterwards?
 
  • #7
Assuming that the projectile launcher isn't perfect, which is more likely, we would have the ball follow a slight deviated path. This really sounds more likely of happening then the conjugation of friction,air pressure and sudden rotation, it's true.
 

FAQ: Physics Laboratory (Projectile Motion)

1. What is projectile motion?

Projectile motion is the motion of an object through the air or other medium under the force of gravity. It is a combination of horizontal and vertical motion, and can be described using equations of motion and the principles of physics.

2. How is projectile motion studied in a physics laboratory?

In a physics laboratory, projectile motion is typically studied by launching a small object, such as a ball or projectile, at a known angle and velocity. The motion of the object is then measured and analyzed using various tools, such as motion detectors and video analysis software.

3. What are the key factors that affect projectile motion?

The key factors that affect projectile motion are the initial velocity of the object, the angle at which it is launched, the force of gravity, and any external forces acting on the object, such as air resistance. These factors can be manipulated in a physics laboratory to observe their effects on the motion of a projectile.

4. What is the relationship between horizontal and vertical motion in projectile motion?

In projectile motion, the horizontal and vertical motion are independent of each other. This means that the horizontal motion is not affected by the vertical motion, and vice versa. However, the two motions are connected by the time of flight, which is the total time it takes for the object to reach the ground.

5. How is projectile motion used in real-life applications?

Projectile motion has many real-life applications, such as in sports like baseball and tennis, where players need to predict the trajectory of a ball in order to make successful shots. It is also used in engineering and physics to study and design objects that are launched or thrown, such as rockets and projectiles in military weapons.

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