Projectile Motion Reflection

What is a projectile? What is the general path of motion? Why?

A projectile is a moving object with gravity being the only force acting on it. If there was any other force acting on the object then it wouldn't be considered a projectile. To further understand this, we shot basketballs and tracked their movement using the video physics app. We started tracking the ball at the moment it left our hands and ended it when it touched the ground. Our basketball moved at constant speed in the x direction while accelerating in the y direction. Even though it accelerates in the y direction, the x is constant so we know that the slope is also a constant. At the balls highest point on the graph it is actually not moving. It reached its peak and now it starts to move downward. 

Our free body diagram shows that the only force acting on the projectile is Fg. It doesn't matter whether a projectile is moving downwards, upwards, upwards and rightwards, or downwards and leftwards the free body diagram would look the same. 

These are my graphs:

Forces in 2D and Circular Motion

1. What does it mean to analyze forces in 2D?

2D stands for two dimensions of space. We can analyze these dimensions separately or individually from one another. This means that it has an x and y coordinate, as opposed to a 4D universe which we live in that has 3 dimensions of space and 1 dimension of time(x,y,z,t). Analyzing a force in 2D means that we need to find a height and length. A force in 1D would only have height, and a force in 3D would need to have height, length, and some kind of curve.

2. How do forces cause objects to move in a circle?

Forces cause objects to move in a circle due to their center pointing(centripetal) net force. When an object is moving in a circle, it is accelerating. Not because its speed is changing, but because its direction of motion is changing. In order to accelerate, it must be experiencing an unbalanced force(net force).


3. What does it mean to be in orbit? How do satellites orbit planets? How do planets orbit the sun?


To be in orbit means that an object follows a path revolving around another object. The gravitational force is the centripetal force, and the pull keeps the object in orbit from floating away(because there is no friction in space). When satellites orbit they are really falling to the earth. Because of gravity they actually end up moving sideways around the earth. Planets orbit around the sun in a circular motion, similar to that of the satellites around the earth.