Week 3 Blog Post

 This week's big question was "What affects a rider's speed down a slide?" 

Lab

In Lab this week, we first discussed different characteristics which affect a rider's speed down a slide. Testable characteristics the class came up with included the rider's weight, what clothes the rider wears, the slope of the slide, and the starting speed of the rider. My group chose to test rider weight to see whether it impacted the speed. We used the ramp, some Hotwheels track, a Hotwheels car, washers, tape, and a stopwatch for our investigation. We started by timing how long it took the car to go down the ramp on its own. Then we timed how long it took with 2 washers, then 4, then 6. Our findings were that there wasn't really that much of a difference in speed when we changed the weight, the explanation for which we then learned in lecture (discussed more below). 

Lecture

In Lecture this week, we focused on the different characteristics that were tested in Lab and how each of them work:

Height

Big Takeaways: the height/steepness of the ramp affects how much time the car has to speed up. The steeper the ramp, the more time the car can speed up. This "speeding up" or change in velocity is called acceleration, and it's caused by a force (push or pull caused by interaction with another object, as stated in the Pressbook reading). The steeper the tilt of the slide, the less the slide is able to cancel out, or act against, gravity. 

Clothing/Friction

Big Takeaways: Friction opposes the sliding of the cars down the ramps. The amount (magnitude) of friction present depends on the clothing or material the rider/car/object is wearing or made of, and how hard the surfaces are being pushed together. (More friction is created by pushing the car down toward the slide than if you let it slide on its own). 

Rider Weight

What we discovered in lab was that rider weight does not affect their speed all that much. This makes sense when you think about how gravity and the slide are working as forces. Gravity is pulling the car, or person, down according to their mass, but the slide is pushing back up according to their mass as well. While the gravity is pulling harder on objects with more mass, the more mass an object has, the harder it will be to accelerate. More opposite force has to be enacted on it in order fo rit to accelerate from its current position. The reason why objects fall at different rates is because the object may be colliding with more air particles and doesn't have the mass to fight against them (the case with feathers). This is called air drag. Without air drag, all objects would fall at the same rate. This made me think of the video we watched on this in my high school physics class, where they dropped a bowling ball and a feather at the same time in a vaccuum and they both fell at the exact same rate. 

Pressbook - Chapter Nine

1. What did you learn?

I learned/was reminded that inertia is the measure of "an object's tendency to resist changes in motion." I usually think of inertia as a bowling ball falling and being less likely to stop than a feather. While this does involve inertia, it's not all inertia is. Inertia refers to an object's resistance to any change in motion- not just going from "moving" to "not moving."

2. What was most helpful?

What I found most helpful were the explanations of Newton's Laws of Physics. I felt that the definitions and explanations were very clear and helped me get a better idea of what each law means. I also think I am better prepared to explain or teach these concepts to kids in terms they'd understand. 

3. What do you need more information on? What questions/concerns/comments do you have?

I would like to learn more about what static friction is and how it works. I understand that it occurs when objects are not moving, but I would like to learn more about how exactly it works. Can static friction cause objects not to move, or does it occur because they are not moving?