Projectile Motion

Big Questions: "What is a projectile?" and "What is the general path of motion? Why?" 

In this lab, we used the Vernier Video Physics app to analyze the projectile motion of a basketball shot into the air. One of my classmates took a video of me shooting a basketball and I used this app  to make a motion map on the video and then it produced X vs. Y charts. The X is the motion in the horizontal direction and the Y is the motion in the vertical direction. A projectile is an object propelled by an external force. The general path of motion of a projectile is a parabolic arc.

For the motion in the X direction:
-Velocity is constant
-Acceleration is always 0
-Never speeds up, slows down or stops
The two equations we derived were:
- Vx=Vxi
-Xf=Vxt+xi

For motion in the Y direction:
-Velocity is changing
-Acceleration is always -10m/s
The two equations we derived were:
-Vy=(-10m/s)t+Viy
-y=1/2(-10m/s)t^+Viyt+yi

Hover Disk- Centripetal Force

Big Questions: "How do forces cause objects to move in circles?" "What does it mean to be in orbit? How do satellites orbit planets and how do planets orbit the Sun?"

To answer these questions we used a hover disc attached to a string. We held the string and spun in a circle--imitating the gravitational pull of the moon orbiting the Earth. In order to analyze forces in two directions, two vectors need to be involved. Vectors need speed and direction. When objects move in a circle, their velocities want them to keep moving in a straight line. However normal forces from seats and doors cause the direction of our velocity to change and causes us to go in a circle. In this specific lab, there is a tension force between the person and the disk--the string. This tension force's direction is inward towards the person. When an object is shot into space, gravity pulls the object down at great speeds. The object is basically falling toward Earth, but misses because the Earth is also rotating. This is how satellites and space stations orbit Earth. The planets orbit the sun because of sun's gravitational force. Since there are no other forces in space, the planets only have the sun's gravitational field. The Earth has a velocity that is perpendicular to the Sun's gravitational pull. We then made an interaction between the person, the disk and the Earth. Between the person and the Earth, there is gravitational and normal force. Between the disk and the Earth there are normal, gravitational and friction forces.There is also a tension force between the person and the disk.