Projectile Motion and Velocity (LAB)

[djtropicana]

This is my first post to this forum!

I'm working on a Lab write up for introductory physics involving projectile motion and velocity.

For the experiment we threw a ball such that its motion was as close to parabolic as possible. A video was taken and using a video analysis program we were tasked with determining whether or not the horizontal component of velocity remains constant - we found this to be true, as well as the equation which described the vertical position of the ball.

The vertical position of the ball was found to be of the form:

y = y_o + v_oyt + (0.5)a_yt²

The problem is a_y, which should be -9.8 m/s² was found to be -11.4 m/s².

The data we collected is a perfect fit with our match equation but I cannot for the life of me figure out why the value for a_y would be off by so much.

The only thing that I can think of is that maybe the spin of the ball while it's in motion is somehow causing the discrepancy between values. Is this a possibility?

Any other explanations would be great as well! Thanks!

 

[rl.bhat]

Hi djtropicana, welcome to PF.
The equation fo the vertical position should be
y = yo + voyt - 1/2*g*t^2.
Try with this.

 

[tomcue]

First of all, great job on conducting this experiment and using video analysis to determine the motion of the ball. It is important to accurately measure and analyze the data in order to understand the underlying principles of projectile motion.

Regarding the discrepancy in the value of ay, there could be a few different explanations. One possibility is that there were external factors affecting the motion of the ball, such as air resistance or friction, which could have caused a slight deviation from the expected value of -9.8 m/s2. Another possibility is that there were errors in the measurement or analysis process, which could have led to a slightly different value for ay.

As for the spin of the ball, it is possible that it could have had an effect on the motion, but it is unlikely to cause such a significant difference in the value of ay. It would be helpful to repeat the experiment multiple times and compare the results to see if the discrepancy persists. Additionally, you could try adjusting the experimental setup to minimize any potential sources of error and see if that affects the results.

In conclusion, while the discrepancy in the value of ay is concerning, it is important to consider all possible factors and sources of error before drawing any conclusions. Further experimentation and analysis may be necessary to fully understand the reasons behind the deviation. Keep up the good work in your scientific pursuits!