Projectile Motion Reflection on Learning

     In our most recent lab, we performed an experiment which helped us to better understand what a projectile is and which forces are acting on it. We began by taking a basketball and shooting it into the air at an angle. By taking a video of this, we were able to create some graphs and visual images that would help us understand the ball's pattern in the air. 

      These screenshots show graphs that each give different information about the projectile (basketball). The two bottom graphs in particular show the velocity of the ball in relation to the amount of time it was in the air (Vx and Vy).  The bottom right graph shows us a line which crosses the X-axis at some point. Looking on the graph, we see that it crosses the axis at around 2.5 seconds. This is the exact time at which the ball is at its peak. It has stopped going up and has not yet started falling down. 

      I think the most important concept I learned from this lab was that all projectiles only have one force acting on them. In this case the force was gravity. All of our work is shown below on our whiteboard:

Forces in 2D & Circular Motion (Big Questions)

Questions:
1. What does it mean to analyze forces in 2D?
2. How do forces cause objects to move in a circle?
3. What does it mean to be in orbit? How do satellites orbit planets? How do the planets orbit the sun?

Response:
      In the past week of physics class, we've started studying forces in 2D. For example, if we were to see a tension force of say 60N acting on an object, we would also be asked to calculate the Fy and the Fx values. This type of work really goes back to geometry where we used SOH CAH TOA to help us find our x and y values. Overall, finding these values can help us to calculate the net force acting on the object and help us to better understand the problem.
      We also performed a few labs during the week that helped us to understand these forces. In our hover disk lab, we learned more about how tension can keep an object moving in a circle. We had a string connected to our hover disks and simply spun the disks around us in a circle. The disk continued to move in a circle around me because I was holding the string (tension force) that kept it going in circles. (Although the hover disk was moving at a constant speed, it was technically accelerating because it was constantly changing directions.) However, if I were to release that string, the disk would fly off in a straight line (90 degrees from the tension string) and continue getting farther and farther away from me.
      This concept of tension keeping an object going in circles also helped me to understand how things can stay in orbit. Instead of a tension force, simply think of a gravitational force. When something is in orbit, it is constantly moving around another object. Think of satellites. The satellites that stay in orbit are technically falling towards the earth at all times. They just go so fast while "falling" that they miss the earth and continue going right back around again. This same idea also applies to the planets orbiting the sun.