Physics 4A (9/14/16 ) Projectile Motion

Physics 4A (9/14/16 )

Projectile Motion

Brett Mccausland

Lab Partner: Myself

Purpose

To use my “understanding of projectile motion to predict the impact point of a ball on an inclined board”.Use kinematics equations of motion in 2 dimensions to describe the motion of a projectile accurately in a way that allows us to make predictions.

Procedure

As depicted below, we set a steel stand on top of the table with a clamp holding one end of a steel tray. The other end of the tray sat on another steel tray that was supported by two wood blocks. The second tray was extended to the end of the table. I taped a piece of paper to the ground were a steel cylinder released from the top would approximately land. The piece of paper had a piece of carbon paper on top of it to mark the paper on impact. Then I measured the distance from the end of the steel track to the point of impact on the paper.

For the second procedure depicted in the image I repeated the previous procedure except for the two papers were taped to the board that was positioned at an angle on ramp. Note the image was taken before the board was positioned to be directly to the end of the steel track.  

Calculations

I measured the height from the end of the tray to the ground, and the horizontal displacement from the end of the tray to the marking measured with a meter stick .Using equation (1) labeled in the photo of the calculations, I found the time that it took for the cylinder to hit the ground.Then plugging time into equation (2) I found the initial velocity of the cylinder, that is the velocity of the cylinder as it left the track. Next I wanted to predict where the cylinder would land on the wood board at an incline. Using the angle measured with a smart phone.  Using equation (3) I solved for time and substituted the value into equation (4) to find distance. The theoretical calculation for distance was approximately 19.99 m. The experimental measurement was exactly 19.99 m, wow!

  

Conclusion and Data Analysis

The values theoretical and experimental matched way more accurately than I expected.There are several reason why the measurements I took were so accurate, and likely more accurate than my classmates. First of all I didn't get over carried away with the incline of the ramp, this made for a smoother transition from one ramp to the other and less speed means less air resistance which we were neglecting to calculate for. Also I made my ramp very secure with tape so it didn't move positions. The launches were so consistent that they on all of the test runs, the cylinder hit the first mark on the paper only slightly offset from center.Also the measurement were done with several meter sticks to ensure that the measurements on the ground were done from the true starting position of the trajectory as seen in apparatus image two.With use of accurate instruments and with the use of the kinematics equations we can very accurately predict the behavior of a trajectory.