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?

Lab Time

In this lab, we wrapped a rubber band over prongs then we pulled it to different lengths (such as 1 cm, 2cm, 3cm, etc)with the electronic force probe. The first time we pulled the rubber band to the different lengths it was just a single-looped rubberband but then the second time, there were two loops. We did this to see if there would be any drastic changes to our data. The data we got from our single looped rubber band looked a little like this: 

1 cm = 0.38 N

2 cm = 1 N

3 cm = 1.9 N

4 cm = 2.7 N

5 cm = 3.5 N

While our double looped rubber band looked like this:

1 cm = 3.1 N

2 cm = 5.3 N

3cm = 8.4 N

4 cm = 11 N

5cm = 12.6 N

We noticed that by double looping the rubber band that there was an increase in force even though we didn't change how far we pulled the rubber band.

Next, we had to create an equation relating the rubber band, the distance we stretched it, and the force need to stretch it. We found an equation by graphing our data and coming up with a best fit line on a graph where the x-axis is the distance in meters and the y-axis is the force in newtons. 

After all this we came up with the equation Fs=kx.

Fs=Force need to stretch the rubberband

K=Elastic constant of the rubber band

X=the distance stretched

Lastly, we wanted to find the energy/work used in this lab. Just like in our simple machines lab we wanted to find the area of the graph which is also the energy but in this lab the area would be different. The area for this lab is in the shape of a triangle so we had to use the forumla to find a triangle which is Area=1/2(Base)(Height)[A=1/2BH] . We used this forumla and just substituted in our first equation Fs=kx. Our area would be equivalent to Us(elastic potential energy, our base equal to "x" and our height equal to "Fs."We later found out that we couldn't use Fs in our new equation so we changed it to "kx." Afterwards we came to the conclusion that the equation to find the elastic potential energy is Us=1/2(k)(xsquared).

Finally we are done with the lab and now know that force is directly proportional to distance, which is the answer to our big question.

Real World Connection

I think bungie jumping is a great example for this lab. When you bungie jump you are stretching a rope "x" amount of distance depending on how much you weigh which is also the force need to stretch the rope.  The more you weigh the farther you will go down meaning that is directly proportional just like our rubber band lab. This is why when you bungie jump they need to know how much you weigh so that they can increase or decrease the amount of rope your using because if they use a long piece of rope and you stretch the rope too much then you might hit the ground leading to serious injury.

Pyramid Lab

Big Question: 

Is the product of force and distance universally conserved (a constant in systems other than pulleys)?

Lab

To start off this lab, we pulled a toy car up a 12cm(vertically) ramp while adding different masses and making the distance of the ramp shorter and longer. The car it self was 250g and we kept adding masses of 250g on it throughout the lab. For our first trial we pulled just the car(250g) up to 9cm  and it took 2.5 Newtons. We then added a mass of 250g to the car so it weighed 500g together. After we pulled the car of 500g up to 166cm and we got a total of 1 Newton to pull the car that long distance. This is when my group started to question what we were doing. We were unsure on what we were "supposed" to get during the lab but we just kept recording data and eventually figured it out. Finally we came up with the conclusion that if we changed the mass of the car or how far we pulled the car on the ramp, we would always end up with the same amount of energy.

A visual drawing of what the experiment looked like
D=distance
M=Mass(the car)
F= Force need to pull/push the mass a certain distance

Real World Connection

Handicap ramps and the great pyramids of egypt use this idea of having a ramp to use less force. Handicaps need these ramps because they can't put pressure or force on their legs(less force) so they have to travel up this ramp (more distance).  These ramps are a real life save for them, it allows them to get to places where they would usually have to walk up stairs. Having a ramp saves time for handicaps and also allows them to put in less effort, making their lives easier.

Pulley Lab

Big Questions

How can force be manipulated using a simple machine?

What pattern do you observe regarding the relationship between force and distance in a simple machine?

Lab 

In this lab we rebuilt the pulley system that we used from the mass vs. force lab. The hardest thing about this lab was probably rebuilding the pulley too because my group and I would always put the string in wrong. No matter how frustrating the string made us, we were still able to accomplish our goal. We found out that it takes 2 Newtons to lift a brass mass .1 meter (10 cm ) without the pulley system and with the pulley system, it only took about 1.3 Newtons to lift a brass mass .2 meters ( 20 cm) which was double what we lifted without the pulley. While we were lifting the brass mass my group also recorded how long the string was. The first time the string was about 20cm  long and the second time it was about 30 cm long. This is when we figured out that force can be manipulated by the distance of the string. We then concluded that if we double the distance then we are also halving the force, which describes the relationship between force and distance.

After we collected all our data we made a bar graph like the one below. We noticed that they all share the same area no matter how tall or wide it may be. Each graph had something different whether it was a high amount of newtons or a long distance but when you find the area you notice that they are all the same. We concluded that no matter what energy or the area would always remain a constant.

Simple Machines

In class we talked about what are simple machines in our daily lives and one that I came up with was a crane. The cables of the crane act as a pulley.  In addition, one that not everybody would think is a lever. On the back of the crane, there is a huge weight that compensate for what is being picked up at the front of the crane. Having a very heavy weight on the back of the crane is essential because it allows a load to be picked up far forward (more distance) at the front of the crane so it can pick up heavier items without tipping over. ( less force)

Mass vs. Force Lab

Mass is related to force? UNBELIEVABLE

During the first week of school my classmates and I started learning about the effects of mass on force. To start off this lesson we were given a manual force probe, an electronic force probe and a set of brass weights with different masses. With these materials my group and I started to measure the amount of force exerted to lift brass weights of  200 grams , then 500 grams  and after 1000 grams, with a manual probe. After we completed lifting each weight and recording the amount of force it took to lift up the set of weights, we repeated the same procedure with an electronic probe so we could get more accurate data.


Once we got all our data we took this information and began to create a graph that will show the relationship between mass and force. To make this graph we needed to put the mass of each weight(kilograms) as the x-variable also known as the independent variable and the force (Newtons) needed to lift each weight as the y-variable or should I say dependent variable. After plotting each point we connected the lines and came up with our "best fit line", which is line that will hit the most scatter points on the graph then this is what my group and I came up with:

Once we were able to come up with this graph we were able to visually look at their relationship and soon enough we discovered  an equation that relates mass to force, and got y=(9.622)M. Looking at our simple equation with a ton of decimals we decided to take  it a step further and concluded that F=10M, which also happens to be Newton's formula.

Physics in the real world? NO WAY!

Everyday humans use some kind of force without even knowing it, and usually this force is to lift up some type of mass. It can vary from lifting a pencil or even picking up a picture frame but either way they ALL  require some force depending on how heavy the item is. For example I picked up a pencil today with ease but when I got home I had to move my desk with was really heavy and it took my dad and I to lift it. The desk took more force in order to move because it has a bigger mass just like the weights in our lab.