Week 20 Reflection

This week in physics we tested and revealed four final result of the catapult projects. I have to say, this was the project so far that I personally enjoyed the most. However, I wasn't so clear on the catapult subject and accidentally made a sling shot (oops!) and had to go back and reconstruct it into an actual catapult. I felt that the project was difficult, as the marshmallow had to complete the distance of exactly three meters and had to land in the bucket. The overall project wasn't that difficult, but the distance limit proved to be an obstacle for me.

I constructed my marshmallow catapult mainly of wood with a rectangular base. It had two wooden pillars with springs connected to them. The springs then connected to a wooden arm that pivoted with the force of the spring. At the end of the wooden arm, there was a shaving cream cap that served as the resting spot for the marshmallow before being launched. A requirement for the project was that there had to be a mechanic for the catapult to be triggered; it could not be merely pulled back and released. I used a screw diver in between two o-rings above the arm board to set the marshmallow in motion. However, the distance depended upon how fast you released the screw diver and where you placed it across the board. This was another obstacle standing in between my marshmallow and the victorious bucket.

On my fourth try, my marshmallow want in the bucket and I then had to calculate its acceleration, force, and velocity from its distance and hang time. The picture below shows how they were calculated.

We also began our new unit, gravitational motion, on Wednesday and worked with it again today (Friday). I discovered that satellites must be launched with a certain velocity in order for them to orbit the earth and it stays up in motion due to both its inertia and the gravitational pull acting upon it. Its inertia pulls the satellite outwards, but the Earth's gravitational force pulls it back it. The balance between the pull and the inertia keeps the satellite orbiting in space.

More to learn with the new unit, but I'll get there! :)

Week 19 Reflection

This week in physics, we explored more with centripetal motion and the force needed for this "center seeking" movement. To recap, last week we discovered that the speed itself of the object is not changing, but the velocity is due to the change in direction. The only force acting on the object in centripetal motion is the force to the center of the circle; its velocity is not a force. However, the two directions form a component path, in which the object turns in between them, creating the circular motion.

In the beginning of the week we completed a velocity vs. radius lab and came to the conclusion that the data formed a hyperbola. We related this to our acceleration unit, as the graph had the same general shape. The points were mostly linear until the line hit some that were off. At first I thought this was skewed data in our experiment, but it actually wasn't. However, generally, the larger the radius, the greater the velocity of the object.

We also started looking at the factors that affect centripetal motion and the force needed to keep the object in a circular path. Centripetal force is the amount of force required to keep an object in centripetal motion and it depends upon the mass, radius, and velocity. In order to get an object to accelerate, it neds a certain force to act on its mass. We knew that force=mass*acceleration and that acceleration=velocity squared/radius. So we then substituted the acceleration formula into the force formula to construct the formula for centripetal force: force=mass*(velocity squared/radius).

Pictures are a little light this week, but I promise more for next week's blog!
Off to test my marshmallow catapult :)

Week 18 Reflection

This week in physics, we began our first unit of the second semester dealing with centripetal motion. Centripetal motion is the circular path of an object in motion an a centripetal force is a force that keeps an object traveling in a circular path. We first began looking at how to calculate the velocity of an an object in centripetal motion, which is circumference divided by the period. The period is the time it takes for one complete revolution of the circle, which depends upon the speed of the object.

We looked at the difference between the velocity and speed of the object in centripetal or "center seeking" motion. It was concluded that the speed is constant, however, the velocity is not. Although the object continues cover how many meters per second, the direction is constantly changing through the motion, which caused the velocity to be inconstant. Velocity has to do with speed and direction, and the direction is changing during the revolution, so it is not consistent.

The string hooked on the object exerts a force on the object to the inside, creating an acceleration in the direction of the center as well. You have the direction of the velocity and the force to the center of the circle, which are component forces. This results in the motion going in between those two forces, creating a circular path around the center.

In addition, we also began looking at the radii of the circles and how they compare to the velocities. We discovered that the faster an object moves, the more force it exerts on the counterweights and the slower it moves, the less force. Next week we will begin looking at the force compared to the radii and will learn new principles from that experiment.

Cheers to second semester!
#TmPhys12