Projectile Motion

Big Question-What is a projectile? What is the general path of motion?

There are 3 different types of projectiles
1) When an object is dropped from being at rest.
2) When an object is thrown vertically upward.
3) When an object is thrown upward at an angle or horizontally.

When there is only gravity acting on an object, it is considered a projectile. In the diagram below, we drew out 4 Velocity v Time graphs. Remember now! The slope of a Velocity v Time graph is ALWAYS acceleration. As you can see, some of the graphs show that the ball is accelerating. The two x-component graphs have a constant slope and velocity. The two y-component graphs depict the ball slowing down until it reaches the highest position. Then, the ball accelerates down while speeding up.

During our post game analysis, we analyzed our graphs and found the slope of everyone's shot. our table worked together to find the average number of our slope and compared it to the class. We realized the the average slope of the entire class was 10.2. Sounds like a familiar number, right? That's because the gravitational pull on Earth is 10N/kg. Gravity was the only force acting on the basketball. This explains why when the ball travels upwards, the velocity slows down. The ball starts to speed up once it reaches the top of the y-axis as it travels downward!

Hover Disk-Centripetal Force Lab

Big Question #1-What does it mean to analyze forces in 2D?

Last semester, we studied forces primarily in 1D. This meant that the fores only had a x-component or a y-component. To start off the year, we are studying forces in 2D. The forces are no longer straight up and down but, at an angle. To make our life easier, we can break up the angle up into x-component and y-component. Forces are vectors! Meaning they have both magnitude and direction (which we learned last year.) To solve for the value of a 2D force, first we break up the direction into the x-component and y-component. Next, we solve for the magnitude of the x-component and y-component by using Trigonometry. (SOH CAH TOA) REMEMBER! THe components of the force can be positive OR negative. We had to find the value of the x-component and y-component separately to find the net force of x and y separately.

Big Question #2-How do forces cause objects to move in circles?

In our first lab of the year, we used a hover disk with a string attached to it. With the disk on, I would hold the string and spin the disk around me in a circular motion. Since there was a string, we know that tension force (Ft) plays a big part in the lab. The center pointing force AKA the centripetal force in this lab was the tension force. The disk continued to accelerate because its direction of motion was constantly changing even if the disk's speed wasn't changing. Later, Ms. Tye showed us that when we let go of the string while the disk is spinning in a circular motion, it ends up going in a straight line tangent to the circle after it's released because the force and velocity are perpendicular to each other!

Big Question #3-What does it mean to be in orbit? How do satellites orbit planets and how do plants orbit the Sun?

To be in orbit means to continually follow a curved path around an object. Like the hover disks, the satellites orbit the planets in the same style. As the string (Ft) acted as the centripetal force to the kick disk, satellites orbit planets due to the centripetal force of gravity. The gravity is centered towards the planet thus, causing the satellite to orbit. Likewise with planets that orbit the sun due to gravitation force as a centripetal force. If the sun suddenly vanished, the Earth and all the other planets will eventually fall out of orbit and continue traveling at a straight line just like the hover disk lab.