Weeks 2 & 3 - Slides

Week 2 & 3 - Slides

News/Introduction

To recap from last week, we discussed making playgrounds safe and fun. We also explored methods of making races exciting (both racers finishing at the same time). From this discovery, we talked about speed and how we can represent this mathematically or through a visual model like a graph.

For our labs and discussion for these two weeks, we looked at slides! While coming up with questions about slides, we needed to tie these questions into our big question of making a question safe and fun. Some questions that we developed for slides were:

What makes a slide fun?
What makes a slide safe?

Looking at both of these questions, we needed to think about things that we can test when we look at slides (our variables). We developed the following list:

Looking at our list of variables, we need to answer a specific question, which is making the slide safe and fun. Using this parameter, we can narrow down our variable list to the ones circled:

We split the steepness and height of the slides. Our final list of variables is: rider weight, slide steepness, slide surface, and slide height. With these variables in mind, we can start our experiment!

New Discoveries

For our experiment, our group studied the "steepness" of the slide. As a result, we developed our big question for slides:

How does the steepness affect the speed of a rider on a slide?

Our independent variable is the "steepness" of the slide, our dependent variable  is the rider speed. In our process, we determined that our control variable would be the height of the slide.

We developed a claim for our experiment: The steepness of the slide affects the rider speed. The steeper the slide, the faster the rider.

This ultimately became our argument for this experiment: The steeper the slide, the faster the rider. However, the length of the slide decreases with the angle of steepness. 

Our group's findings are as follows:

We determined our rider's speed using some algebra and a speed formula:

 

So as you can see, we have determined that the angle of the slide/steepness does impact a rider's speed. Another important distinction to make is that as the slide gets steeper, the shorter the slide. For our experiment, distance does not matter. Graphically, we can represent this:

 

We see that our line is not linear. But what about the other groups? What did they find in their research on slides? 

Connections

When we look at slides, especially with making them fast and fun, we looked at slide height, rider weight, and slide steepness. What did we find out? But first, we also learned a new term: velocity. We define velocity as the change in position over time. 

 

Velocity can also be positive or negative. If the velocity is positive, we are moving away from the origin. Conversely, if we have a negative velocity, we are moving towards the origin point. Another important term to learn is acceleration: the change in velocity or direction.

 

With acceleration, changes can be made by speeding up, slowing down, or changing direction. 

Height

The higher the slide, the faster the speed of the rider. When we look at the force of gravity, on a higher slide, there is more time to accelerate (a.k.a. get faster). This also means that there is a greater distance, and a higher height means  greater potential energy for the rider. We can represent this using a position vs. time graph

Steepness

Steepness/angle of the slide also affects the speed. The steeper the slide, the faster the rider will go. This has to do with our previous mention of acceleration. The acceleration will change with the steepness of the slide. This is due to gravity (which is estimated to be about 10 m/s / s). Gravity pulls straight down, so of course as the slide gets steeper (to vertical), the pull of gravity will be stronger.

Rider Weight

Rider weight does not impact the speed of a rider. In order to understand this we need to look at gravity by dropping paper balls. 

If we drop a loose paper ball and a tight paper ball, which one wins? The tight paper ball will win because there is less air flowing through it. The force of gravity is the same; however, there is less air resistance (air drag) on the tighter paper ball.


Surface

Surface also impacts the speed of the rider because of friction. When we look at someone on a slide we see several forces acting on it:


This made us think about why some slides have bumps. Some slides have bumps to reduce speed, acceleration, or friction. This is also to make the slide exciting but safe.

Newton's 1st and 2nd Laws

What does this mean? We have started to learn about how these forces act on a rider on a slide. However, we can wrap this up with looking at Newton's First Law: An object will continue in its current state of motion until acted upon by an outside force.
 
Another important law we learned about is Newton's Second Law: F=ma : Acceleration is in the same direction of the force, and is inversely proportional to the mass of the object.


The Future 

Next week, we will continue our physics and playgrounds exploration when we look at swings. 


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