Projectile Motion Lab

Projectile Motion Lab Description

The Projectile Motion Lab was the first project of the year in AP Physics. In this lab we explored all of the components learned in Unit 1- Kinematics. We were first instructed to design a projectile motion device in class. The device had to fit on a platform of 116cm x 72cm, have an assembly and set up time of under 3 minutes, have a modifiable variable that altered the exit velocity of the projectile, and have a projectile exit velocity of at least 2 m/s or more. After designing and building our device, we had to modify the changing variable to have at least 3 different positions so that we would be able to take a minimum of 3 trials from each position. After recording our procedure and data, we used the modifications to predict where the projectile would land when we modified our device. Using the kinematics equations, the data we gathered, and exact measurements of our device, we predicted where our projectile would land from each modified variable. We then designed a landing target for the projectile to hit. We calculated to have a target distance and an error rate so we would know how big to make the target. In the final testing of our device, we ran 3-5 trials attempting to hit the placed target every time. The height of the table was set somewhere between 0.7m and 2m. The hight was determined on the day of device testing, so we had to predict our projectile's landing on the day of testing.

When designing our projectile motion devices, the class was provided with hotwheels tracks, hotwheels, and a variety of balls to use as projectiles. Our group began by experimenting with the hotwheels tracks and cars, but were unimpressed by the unreliability of the projectiles landing distances. However, we were impressed by the hotwheels slingshot used to catapult the cars forward. We decided to construct our own version of the slingshot. After many different designs, we decided on the slingshot seen below. Our main issue was finding a projectile that could be launched from our device without breaking due to the large amount of stress from being pulled back on the rubber band with so much tension. We ended up using a broken pencil. We drilled two holes into the pencil and twisted a paperclip through the holes so that it could be hooked onto the device. Below is my lab report that describes our procedure, data, observations, analysis, calculations, and much more.

Evidence of Work

Content

Velocity - Velocity is the speed of the projectile. We calculated velocity using the equation v=d/t. By dividing the change of horizontal position (in meters) by the calculated time (in seconds) we were able to find the velocity of the projectile (m/s) during each trial.

Acceleration - Acceleration is the rate of change of the velocity of an object with respect to time. Our projectile fully accelerated in a fraction of a second as it was launched from the slingshot. I calculated the acceleration of the projectile by dividing the average exit velocity of each trial by the 0.01 second it took for our projectile to fully accelerate.

Free Fall - A free falling object is an object that is falling under the sole influence of gravity. As soon as the projectile has been released from our device, it is in free fall.

Normal Force - The normal force is generated as a result of a force against a solid surface. As per Newton's third law, the surface will exert an equal and opposite force on the object in contact. If an object is resting on a flat surface, then the normal force will be working to counter the weight of the object due to gravity.

Gravitational Force - The force of attraction between all masses in the universe; especially the attraction of the earth's mass for bodies near its surface. The Gravitational Force on Earth is 9.8 m/s^2.

Tension - Tension is the force transmitted through a rope, string or wire when pulled by forces acting from opposite sides. The tension force is directed over the length of the wire and pulls energy equally on the bodies at the ends.

Frictional Force - Friction is the force that resists motion when the surface of one object comes in contact with the surface of another.

Applied Force - Force which is applied to an object by another object.

Spring Force - When a metal spring is stretched or compressed, it is displaced from its equilibrium position. As a result, it experiences a restoring force that tends to retract the spring back to its original position. This force is called the spring force. It is a contact force that can be found in elastic materials.

Drag - Drag is the force of air resistance. The force exerted by the air on things moving through it is known as air resistance. Typically, this force is applied in the opposite direction as the object's motion, slowing it down

Newton’s First Law - Objects in motion will remain in motion and objects at rest will remain at rest when there are no outside forces acting upon them.

Newton's Second Law - The acceleration of an object is dependent upon two variables - the net force acting upon the object and the mass of the object. For a body whose mass m is constant, it can be written in the form F = ma, where F (force) and a (acceleration) are both vector quantities.

Newton's Third Law - Every force has an equal and opposite force.

Block and tackle - A system of two or more pulleys with a rope or cable threaded between them, usually used to lift heavy loads.

Circular motion - A movement of an object along the circumference of a circle or rotation along a circular path.

Centripetal Acceleration: The property of the motion of an object moving in a circular path. Centripetal means towards the center. The equation for centripetal acceleration is ac=v2/r.

Period: The time for one revolution around the circle. Represented by T.

Gravity - Mutual attraction between all things with mass or energy.

Orbits - The path of a celestial body or an artificial satellite as it revolves around another body due to their mutual gravitational attraction.

Energy - The ability to do work. Energy is the force that causes things to move.

Gravitational Potential Energy: The energy an object has due to its position at a height or in a gravitational field. The equation for gravitational potential energy is: Ug = mgh (gravitational potential energy equals mass times the acceleration due to gravity times height). Potential energy can be spring potential energy or gravitational potential energy.

Kinetic Energy: The energy of an object due to motion. The equation for kinetic energy is: K = 1/2mv² (kinetic energy equals one half times mass times velocity squared).

Thermal Energy: The energy contained within a system that is responsible for its temperature. Heat is the flow of thermal energy. The equation for thermal energy is: Eth=W=Fk𝛥x.

Reflection

This project was a great way to start the year in AP Physics. I learned a lot about how to apply equations to real life situations and was happy to see modifications made on paper transfer to our physical device. Two characteristics I displayed well during this project was critical thinking and character. Our group as a whole had good critical thinking skills as we over came challenges by generating creative solutions. Our device was very different from the rest of our classmates, so it was hard to ask our peers for help, causing us to think deeply about the problems our device was facing and how to fix it. I also had good character as I came to class every day ready to focus and make advances in our design and calculations. I always came to class with a positive attitude and was ready to motivate my group to stay focused and make progress.

However, our group was not perfect. Two things we could have done better was collaboration and conscientious learning. It was taking us a very long time to overcome the challenge of figuring out what projectile could be launched from our device. Once we had finally came up with a solution, it was the end of the week. In order to collect all of our data in time to be ready for calculations the next week, we had to send our device home with one of our team members. This team member had to run and record all the trials over the weekend. While he was happy to do so, if we had managed our time better we could have avoided this outcome. Due to this we also had uneven collaboration because he carried all the responsibility for recording the trials. From this experience I learned the importance of planning the amount of time allowed for each part of the project so that I won't find my group in a similar position in the future. Overall this was a great project because I learned how to apply kinematics equtions to real situations, I got to overcome challenges in creative ways, and I learned the importance of time management so that I wouldn't make the same mistake in future projects.