Projectile Motion Lab

This week, we went down to the gym to shoot basketballs and use the Vernier Video Physics application on our iPads to observe the projectile motion. Projectile motion is when an object is only acted upon by force of gravity.

The Vernier Video Physics app made graphs for the x component and y component:

x (position and velocity)

In the top graph, the slope is constant.
In the bottom graph, the line is relatively constant without a slope.
Since there is no slope, there is no acceleration, so there is no net force

y (position and velocity)

In the top graph, the slope is not constant so it is accelerating.
In the bottom graph, the slope is negative, and the graph should intersect the x axis.
The line shows the path of the object, in this case, a basketball going up, and when it crosses the x axis, it stops (time = 0) and begins to fall down.
There is a slope so there is acceleration.

Then, as our table combined the graphs, we came up with an average slope of -10 m/s^2. We collectively agreed that acceleration is due to gravity.

Forces in 2D and Circular Motion

                                        

What does it mean to analyze forces in 2D?

To measure both the x and y components. Once the forces are broken up into both the x and y components, we use SOH, CAH, or TOA to find the magnitude of Fx and Fy. then we can find Fnetx and Fnety.  

How do forces cause objects to move in a circle? 

As an object moves in a circular motion, it changes direction. An object moving in a circle is accelerating. It accelerates because the direction of the velocity is constantly changing. The net force acting upon an object is facing towards the center of the circle. The net force is acting as a centripetal force. Without net force, an object would continue to move in a straight line. In our lab, we tested this force by attaching a string to the hover disk. We spun the disk around and felt the inward force as the disk was hovering around us. When released the string, the hover disk glided in a straight line because there was no centripetal force acting on it. 

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

To be in orbit means to be traveling around another object, such as the moon. Satellites orbit because of the gravitational pull of Earth. Since the planet is rotating and since the satellite is free falling, the satellite will move sideways and fall into the orbit of the planet. Just as the moon orbits the Earth because of the earth's gravity, the Earth orbits the sun because of the pull of the suns' gravity.