Rubber Band Inquiry Lab

This week in class we explored the way that energy is stored in objects using a metal ramp, rubber band, and force probe.

The purpose of this lab was to find how energy can be stored for later and to discover the relationship between a rubber band's force and how far it is stretched.

For the first part of this lab,  we measured the force of the rubber band when we stretched it to a  specific distance (1cm, 2cm, 3cm, 4cm, and 5cm). We noticed that the farther the rubber band was stretched, the more the force increased. Then, we repeated the trials after doubling the rubber band, causing the force to increase even more. If we stretch a rubber band, the bonds are storing energy. The more we pull, the more energy we have.Rubber can store more energy than material such as wood because they have more stretchy bonds. The stored energy is then released if we let the rubber band go.

The trials that we completed showed us that it takes more force to stretch a rubber band farther. In other words, the farther the distance the greater the force.

We concluded that the force is the ELASTIC SPRING FORCE. This was when we lerned a new formula (YAY!)

SPRING FORCE EQUATION:

Fs =K*X (similar to y=mx+b)X= stretch distanceFs=spring force 

K=slope or "k value" (see below)

IV=X (distance)

DV=Y (force)

Slope of x and Fs is called the "k value" or elastic spring constant. The "k value" is different for every rubber band (some atoms have tighter bonds than others) just like "g" (Earth's gravitational force) is different for every planet


Potential energy is stored energy*

Real World Connection:

Bungee jumping is quite similar to the lab that we performed this week. As the person jumps and falls the cable that connects them to life is pulled more and more by the weight of the person. The more force that is applied to the cable, the more energy is stored in the bonds. When the cable reaches it's maximum "k" value, or when the rubber bands is stretched as far as it can go, the energy is released, causing the bungee jumper to shoot back up into the air like a sling-shot.

Pyramid Lab

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

This week, our new table completed a lab using metal ramps, plastic carts with weighted masses, and a device that measured and graphed force electronically(force probe). In a series of trials, we measured the height of the ramp and the mass of the car ( both variables remained constant throughout the duration of the lab. For our table, the height was .11m and the mass was .75kg) as well as the force and distance which varied for every trial. We used the force probe to find and graph the force as we pulled the cart up the ramp. Using the force and distance, we calculated the work for each trial. Work is defined differently for physicists than the work that our parents do every day or the work that we as students must complete at home every night. Work is the product of force and distance, or W=F(N)d(m). This kind of work is measured in Joules (J) which is a type of energy. After measuring and graphing the data, we compared the work in each of the 3 trials. In class we learned that the work in each trial was within a 10% range of each other. Because our calculations were a tad off, the work was not exactly the same, but a 10% range is fairly close. This answers the main question for this lab. YES WORK IS CONSERVED.

                                                                              
                                                    
                                                              

Real World Connection: When handicapped people in wheelchairs need to move about more convieniently and accesibly, they use ramps. For example, a handicapped man needs to get into his car. Instead of having others lift the entire weight of the wheelchair plus himself up the sum odd two feet that it takes to get the chair into the car, he can use a ramp and although it covers more distance, the ramp requires less force for the man and makes his life easier due to the fact that force and distance are inversly proportional, which we learned last week. In fact, both methods for lifting the wheelchair require about the SAME AMOUNT of WORK because work is universally conserved.

                   

Pulley Lab

Big questions: 

1. How can force be manipulated using a simple machine?

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

 In this lab, we created 2 simple pulleys that supported weights of different sizes and forces. In part 1 of this activity, we created a pulley with 2 (200g) weights that allowed us to lift one of the 200g masses from the table to a height of 10cm. Using the knowledge that we acquired last week, our table knew that it required 2N of force to lift the weight. Since we used the same amount of force we had to pull the same distance to lift the weight.

In part 2, we were challenged to build a second pulley using 2 different weights (100g and 200g) meaning that we would only use 1N of force.Because we cut the amount of force that we used in half, our table had to pull for twice the distance in order to lift the weight.

After completing this task and recording our data on the board, we noticed a pattern and learned that force and distance are inversely proportional, meaning that less force requires more distance.

What I learned from last week:

g=10 N/kg
m=200g or .2kg
F=Force of gravity or weight

F=gm --> F=(10 N/kg)(.2kg) --> F=2N


Real world Connection:
In my room, I have a window with a handle that must be rotated if I want to open it. Although the window only moves slightly for every rotation  and I have to move my hand many times, I only need a small amount of force to open my window instead of using more force to get it done in a shorter amount of time.

*More force=less distance and less force=more distance

Mass vs. Force Lab

Purpose: The purpose of this lab was to measure the relationship between mass and force through careful calculations, predicting patterns, and creating graphs. In addition, we learned about the best fit line and how we solve for the slope of a line.

Summary of Big Questions: 

"How do we measure force in a reliable and repeatable way?"

We measure force in a reliable and repeatable way by predicting patterns in our data.  Our table measured the brass weights the same way  (held high, not touching any surfaces..etc.) to get the most accurate data. By using different weights to achieve different results, we eventually began seeing trends (the mass in kilograms required 10 times the force in Newtons). After consistent results, we made predictions that were proven correct with further measurements.

"What is the relationship between the mass of an object and the force needed to hold it in place?”

By using our graph,  our table was able to discover that it takes 10 Newtons of force to support each kilogram of mass. Often times the patterns were not precisely 10 because the tools that we used to measure the force were not exact but by using the best fit line (the line that best captures the pattern of the points) and finding the slope (rise/run) we were able to find the pattern in the graph which was

g(Force)=10N/kg(mass)

Data:
    




Real World Connection: Architects need to know Earth's gravitational constant (10 N/kg) because they need to know how much weight will support their structure from collapsing due to gravity. In a way, force is almost like magnets. Gravity is constantly pulling us towards the earth and in order to stop that force, an architect needs 10 Newtons of force per kilogram or weight in their structure. Weight is the force of gravity that is pulling the structure NOT the mass and the force of objects are different because different objects have different  masses but gravity STAYS THE SAME (10 N/kg).