Projectile Motion
Partners: Mary Schaude and Hunter McCabe
Date: 4/9/14 - 4/22/14
Date: 4/9/14 - 4/22/14
Purpose
To determine the initial velocity and predict the range of the projectile.
Theory
When deriving the equation, time must be solved first using the third kinematic equation. The equation must be manipulated into a quadratic formula because none of the variables cancel out (this done after the delta y is moved to the side with the other variables).
After the equation for time is derived, it is substituted in for "t" in the range equation.
In addition, Vox can be replaced with Vcos(theta) while Voy can be replaced with Vsin(theta). The finished equation is shown below:
Experimental Technique
![Picture](/uploads/2/6/5/9/26590312/1037006.jpg)
Apparatus:
- Mini Launcher
- Launcher bracket and clamps
- Steel or glass ball
- Photogates
- Photogate bracket
- Plumb bob
- Measuring tape
- Targets and Carbon paper
- Set up the launcher to launch at an angle.
- Use two photogates to measure the initial launch velocity. Each member of the group should use a different launch speed or a different angle. Fire at least ten times and determine the average velocity.
- Measure the initial launch height of the ball. To do this, measure from the floor to the bottom edge of the ball pictured on the side of the launcher. We use the bottom edge because it is this edge that will make the mark on the target.
- Predict the range of the projectile. In order to make this prediction, you will need to derive an equation for range in terms of the initial velocity and the launch height. Please include the appropriate diagrams with this derivation.
- Use a plumb bob to mark the initial launch position on the floor. Please do not write on the floor. Instead tape an index card under the launch position and place your mark on the card.
- Place your target at the predicted range and Launch the first shot. Mr. Bowman would like to witness this first shot. Accuracy will be included in the grade for this lab.
- Fire at least ten shots and measure the average range.
- Compare your predicted range to the actual range using percent difference.
Data
Analysis
Conclusion
In this lab, the uncertainty in the range measurement was +/- 0.049 m. When comparing the predicted and measured ranges, I saw that the average measured range was 0.016 m smaller and all the measured ranges were relatively close to the predicted value. The only real source of error, besides me taking the paper off the floor, would be rounding errors. I do not believe wind resistance was a factor because we were indoors.
References
http://eschaude.weebly.com/projectile-motion.html
http://lahsphysics.weebly.com/projectile-motion-lab.html
http://lahsphysics.weebly.com/projectile-motion-lab.html