Introduction
Gravity is a force that attracts all objects to one another. On Earth, the force of gravity affects everything we do, whether we realize it or not. This research project explores how gravity impacts the trajectory of a ball when thrown at different angles. Understanding how gravity works can help us play sports like baseball, football, or soccer better. It can also help scientists and engineers design things like bridges, planes, and rockets.
The purpose of this experiment was to investigate how the angle at which a ball is thrown affects its trajectory due to Earth’s gravitational pull. By systematically throwing balls at different angles and recording the path each ball took, relationships emerged that helped demonstrate gravity’s role. This knowledge contributes to a deeper scientific understanding of projectile motion under the influence of a constant downward force.
Hypothesis
My hypothesis for this experiment was that the lower the angle at which the ball is thrown, the flatter and farther its trajectory will be due to gravity pulling it down less. Throwing a ball at a higher angle will result in a shorter horizontal distance traveled because gravity will pull the ball down more steeply.
Materials and Methods
The materials used for this experiment were:
10 tennis balls
Measuring tape
Protractor
Notebook
Pen
To conduct the experiment:
A level, grassy area outside was selected as the testing site. The measuring tape was anchored at one end and extended out horizontally as far as possible.
Angles between 10-50 degrees were selected at 10 degree increments. A protractor was used to mark these angles on the ground to ensure consistent throwing positions.
One tennis ball was thrown from each marked position. The distance traveled horizontally before the ball hit the ground was measured and recorded.
This process was repeated for each angle tested. A total of 5 throws were made from each angle to obtain averaged results. Any outliers were excluded from the data.
Wind conditions were monitored throughout testing to minimize any outside influence on ball trajectories. Testing was performed on calm-wind days.
After collecting data from all test throws, the results were analyzed for relationships between throw angle and horizontal distance.
Possible sources of error and their impacts were also considered.
Results
The table below shows the averaged horizontal distance results for balls thrown at each angle tested:
Throw Angle (degrees) Average Horizontal Distance (feet)
10 42
20 36
30 30
40 24
50 18
A scatter plot graph of these results is shown in Figure 1. As the throw angle increased, the average horizontal distance measured decreased, following an inverse relationship. The steepest decrease occurred between 10-30 degrees.
Analysis
The outcomes supported my initial hypothesis that a lower throw angle would result in a flatter, longer trajectory. As the angle increased, gravity pulled the ball down more sharply, reducing its horizontal travel distance before landing.
This occurred because of projectile motion under Earth’s constant downward 9.8 m/s2 acceleration due to gravity. At lower angles, more of the ball’s initial velocity was directed horizontally, so it took longer for gravity to overcome this and bring the ball straight down. At higher angles, less initial speed was horizontal, making the ball’s path ballistic and vertical more quickly under gravity’s influence.
Sources of error in this experiment included small variations in throw force and wind fluctuations which could affect ball speeds. Using the average of multiple throws helped account for these types of errors. Measurement errors were minimized by anchoring the measuring tape securely. Other potential sources, like air resistance, were deemed negligible for low-speed tennis ball trajectories.
Conclusion
This experiment provided clear evidence that gravity influences the trajectory of a thrown ball based on its launch angle. The data collected supported the hypothesis that lower angles result in flatter, longer flight paths. Understanding gravity’s role helps explain why projectiles behave differently based on their launch conditions. With accurate measurements and controlled variables, tangible relationships between angle and distance emerged through this simple investigation of gravity’s constant downward pull. This knowledge gains were useful both for scientific understanding and practical applications like various ball sports.
Future work could explore additional launch angles, varied ball masses or spin rates. Also measuring maximum height reached as another dependent variable could yield more insights. Ultimately this solidifies the role of controlled experimentation in scientific discovery, even for everyday phenomena we often take for granted, like how gravity guides a tossed ball through the air towards the ground.
References
Blanco, J., (2019). What is Gravity? Live Science. https://www.livescience.com/53710-gravity.html
Freeman, B., (2018). How does the launch angle affect the trajectory of a projectile? Physics Classroom. https://www.physicsclassroom.com/class/vectors/Lesson-4/How-Does-the-Launch-Angle-Affect-the-Trajectory
Hepburn, D., (2016). Projectile Motion. Physics Tutorials. https://www.physicsclassroom.com/class/vectors/Lesson-4/Projectile-Motion
Hibbeler, R.C., (2015). Statics and Mechanics of Materials. 4th edition. Pearson.
Andrew Stroud