Title: Projectile Motion
Partner: Kelly Schneck
Date: 10-20-15
Partner: Kelly Schneck
Date: 10-20-15
Purpose
The purpose of this lab is to derive an equation to predict the range of the projectile and compare the predicted range with the average range once tested.
Theory
Experimental technique
In the lab, we began by setting up a launcher at a specified angle. Then we shot a ball out of the launcher, using Photo Gates to measure the initial velocity. A plumb bob was used to aid in the measurement of the height of the ball in relation to the ground.
Ten shots were fired onto carbon paper located at the predicted range. With each launch, the carbon paper marked where the ball landed. Each mark was measured to find average range.
Ten shots were fired onto carbon paper located at the predicted range. With each launch, the carbon paper marked where the ball landed. Each mark was measured to find average range.
Data
After firing 10 shots, I found the average range to be 289.37 cm.
Analysis
Conclusion
After firing all 10 shots, I found a percent difference of 6.5% and an uncertainty of about 18 cm. The average range of the projectile was greater than the predicted range.
Sources of error could be parallax in taking measurements for the angle of the launcher and height of the bottom portion of the ball in relation to the ground. Error in technology such as the Photo Gates could cause slight variation in the initial velocity of the ball. Both examples of error could cause the components of the derived range equation to be inaccurate, causing the predicted range to be off. As we experimented, the force to which the string was pulled to launch the ball was found to affect how far the ball traveled. Since the initial velocity was calculated at different times than the data was taken, the range of the ball could have been affected that way.
I do not think wind resistance was a factor in this experiment. The weight of the ball is heavy enough to not be significantly affected by wind resistance. Also, if wind resistance were a factor, the ball would have been slowed down causing it to land short of the predicted range. The ball traveled farther than expected, therefore wind resistance was not a factor.
Sources of error could be parallax in taking measurements for the angle of the launcher and height of the bottom portion of the ball in relation to the ground. Error in technology such as the Photo Gates could cause slight variation in the initial velocity of the ball. Both examples of error could cause the components of the derived range equation to be inaccurate, causing the predicted range to be off. As we experimented, the force to which the string was pulled to launch the ball was found to affect how far the ball traveled. Since the initial velocity was calculated at different times than the data was taken, the range of the ball could have been affected that way.
I do not think wind resistance was a factor in this experiment. The weight of the ball is heavy enough to not be significantly affected by wind resistance. Also, if wind resistance were a factor, the ball would have been slowed down causing it to land short of the predicted range. The ball traveled farther than expected, therefore wind resistance was not a factor.
References
Giancoli, D. (1998). Physics: Principles with Applications (5th ed.). Upper Saddle River, N.J.: Prentice Hall.