Rubber Band Cart Launcher Lab

Big Question:
"How are energy and velocity related?"
-From our lab, we were challenged to work with many different equations that helped us relate energy to velocity. We used the equation for spring potential energy, kinetic energy, and gravitational potential energy. By using these various equations, we were able to calculate values and relationships between energy and velocity.


Lab:
This lab was like a sequel to our previous lab with the rubber bands. We used the same setup with the air track and rubber band. Only this time instead of finding the force required for the rubber band, we were testing an entirely new concept of velocity. 
      We used equations we learned in class like the kinetic energy equation, K = 1/2mV^2, to help us calculate the velocity. 
      Our testing was basically just pulling the red glider back a certain distance in meters, then letting it go on the air track. After being released, the glider would pass under a velocity recorder. We connected this recorder to our labquest devices and were able to find the speed of the glider being pulled back at various distances. 

(Whiteboard showing our data plotted on a graph using Vernier Graphical Analysis.)

      After gathering all our data, we averaged it, squared it, and from there we could plug it into our equation to find the energy if we wanted to. This lab wasn't really about finding the energy, it was mainly just about getting practice with velocity and how it can relate to different forms of energy.

Today's World:

      In our world today, these concepts of potential energy, kinetic movement, and velocity can be easily seen at any amusement park. Roller coasters may seem like fun and games, but there is actually a great deal of physics involved in these rides. When the car is stalled at the top of a hill on the roller coaster, it still has potential energy. When it slowly creeps forward and starts to plummet down the track, the potential energy is converted to kinetic energy and this movement carries the car around the rest of the track because no energy is lost, it only changes forms.

Rubber Band Lab

Big Question:
"How does the force it takes to stretch a rubber band depend on the AMOUNT by which you stretch it?"
-After completing this lab, we found that by stretching a rubber band over a distance, the more force is required the farther you stretch.

      We began this lab by putting a rubber band on an air track:

(We didn't use the red piece^)

      Our testing involved stretching the rubber band over various distances and recording how much force was required to hold the rubber band AFTER it was stretched. We were creating potential energy, so we wanted to measure how much force was required to hold the rubber band, not pull it. 

      We used a force probe to record the force and completed two different types of tests. First we measured the force of 5 separate distances with the rubber band only single stretched; we then double stretched the rubber band and measured the same 5 distances. After all of our testing was complete, we recorded our data and found that the amount of required force to hold the rubber band was increasing.

   Single band:                   Double Band:           

1cm - 0.90N                    1cm - 5.20N

 2cm - 1.05N                    2cm - 6.90N

 3cm - 2.10N                    3cm - 7.78N

   4cm - 2.75N                    4cm - 10.08N

   5cm - 3.60N                    5cm - 11.32N

In our world today, we can see this principle being used especially by hunters. Many hunters prefer to use whats known as a compound bow. These are very heavy bows and require great amounts of force to pull back. The farther you pull back the string, the more force you need. When you pull the string back all the way, you've created potential energy.

Fun Fact: Compound bows use pulley systems. This means that you can pull the string back the same distance as a normal bow, but use less force because of the pulley system.

Pyramid Lab

      In this lab, we were using simple car and ramp systems to measure the relationships between force, distance, and work.

      Our experiment started out with a 750g car. We placed it on a ramp and attached a force probe to it. For our first test, we pulled the car up the ramp for a distance of 1.4m. (This required 0.36N of force) For the second test, we made the ramp steeper, and dragged the car a distance of 1m. (This required a force of 0.53N) For our final test, we made the ramp even steeper, and pulled our car a distance of 0.8 meters. (Requiring a force of 0.65N)

      After we gathered all our data, we found that the work required to pull the car in all three tests was roughly the same. From our three tests we averaged 0.52J of work was required. So basically, we put in the same amount of effort each time, the only thing that changed was how far the car traveled up the ramp.

      In our world today we can apply this notion to anything that involves a ramp. Movers for example, use ramps all the time to load and unload heavy objects. From our tests we noticed that the longer the distance of the ramp, the less force was required to pull the car. Movers use this notion when unloading couches or refrigerators. Its much easier to push a couch up a ramp instead of lifting it straight off the ground 5 feet in the air.

(The longer the ramp, the less force you need to pull the object.)

(These movers probably couldn't lift that piano straight into the truck. Thats why they're using a ramp.)

Simple Machines: Pulley Lab

      In our most recent lab, we spent time working with various pulley systems to help understand the relationship between force and distance.

      During the first few days of the lab, we constructed a simple pulley machine using only one pulley, a brass weight or 200g, and a length of string. We basically just did a few tests to see how much force was required to move the weight 10cm with and without a pulley.

  Our results ending up showing us that it required roughly 1N to move the weight 10cm with a pulley, and roughly 2N to move the weight 10cm without a pulley. We can conclude from these short tests that with one simply pulley, we only have to use half of our force to move an object that would normally take twice the force. This concept is very practical in the real world. Today workers everywhere use pulleys to get their job done with less effort.

      After completing the work with out simple pulley systems, we moved on to more complex pulley systems with more strings. A very useful tool we used in this lab was the force probe. This device allowed us to measure the amount of force being used to pull the brass weight with various pulley systems. 

 

(We connected these force probes to our labquest devices and were able to read how much force was being used to lift our 200g mass.)

      We used a simple pulley, one with two strings, and one with four strings. As we completed our tests we found out that less force was required with more stings/pulleys. For example, with a simple pulley, the required force was almost 2N. But with a four string pulley, the required force was 0.5N. From our work it was clear to us that the more complex pulley system we had, the less amount of force was required.

(This whiteboard shows our work in graph/data table form. After graphing all of our work we were able to see that each test took up the same area on the graph.)

After completing this lab, I was able to see how these simple pulley systems play vital roles in the real world. Workers today, especially at docks and construction sites, use pulley systems to lift heavy weights and get their jobs done easier. 

 

(This is an example of a simple pulley system used on boats to lift heavy cargo onto their decks)

(This crane also has lots of pulley systems which allow it to lift items normally to heavy for the amount of force it uses)

Mass vs. Force Lab

      In the past few days of Physics class, we've been working on a lab that deals with mass and force. In the actual lab itself, I, along with 3 other partners, would put various "brass masses" on a scale and record how how many Neutons each weight would have according to its mass. 

      In our lab we found that the number of Newtons was directly proportional to the mass of a weight. For example, if one weight had a mass of 0.5kg, then it would be equal to 5N; or if a weight had a mass of 1kg, then it would be equal to 10N. We plugged our data into the slope formula and the equation of a line formula and ultimately we came up with the equation f = 10m. (force = 10 X mass)With this equation we would be able to predict how many Newtons a weight would have without going to all the trouble of putting it on the scale.
      In the real world today, gravity is used in almost everything we do; it's what holds us down to the planet. In our lab, gravity was a key factor that helped us determine the force of a certain object. When holding our scale still, gravity would constantly be pulling down on our brass masses which would let us know how many Newtons each mass had. Just as gravity was pulling down on our weights, it also pulls down on everything else on the planet. For example, if we jumped out of a plane, gravity would pull us down. Just as if we held up a weight, gravity would also pull it down.

      This lab was overall very helpful and gave all of us good experience working with data, graphs, and scientific formulas. I can now better understand the connection between how gravity is used in experiments, and how it applies to everything around me.