Pyramid Lab

The BIG Question?

        - Is the product of force and distance universally conserved, which means a constant in systems other than pulleys?
     

     In Physics class this week we wanted to see if energy (in the SI unit Joules) was universally conserved.  Three books were stacked on a table and then a ramp was placed at an angle on the books.  Then a cart was placed on the ramp which was 750g.  The cart was manually pulled up the ramp and we used an electronic force probe to measure the force required to pull it up.  Here are our results

       Trial #1
          Force: .25 N
          Distance: 1.33 m
          Work: .3325 J

       Trial #2
          Force: .50 N
          Distance: .7 m
          Work: .35 J

       Trial #3
          Force: .4 N
          Distance: 1.6 m
          Work: .64 J
The first two results were consistent with our hypothesis but our third trial was very random and different.  After trying multiple times we got the same answer.  This is just down to human error and the fact that we are a bunch of sleep deprived high school students who can't focus for more than ten seconds at a time.  

From this lab, we were able to see that energy is conserved, and we discovered the relationship between its two factors.

The relationship with Force and Distance is inverse.

• When the force goes UP, the distance goes DOWN
• When the distance goes UP, the force goes DOWN.

Real Life Connection:

For those people in our world who have to use a wheelchair ramp, they are putting in the same work as those who use the stairs.  Those who take the stairs cover less distance but use more force to get themselves up.  Those in wheelchairs inversely then cover more distance but use less force.  

The Pulley Lab

The Big Question

• What pattern do you observe regarding the relationship between force and distance in a simple machine?
• How can force be manipulated using a simple machine?

Introduction:

     This week in Physics class we performed a lab that demonstrated the relationship between mass  and the amount of force needed to hold it in place.  This was done using "simple machines" (a clever title since making one was actually very difficult).  We were asked to find how many Newtons were needed to lift .2 kg 10cm in the air without the pulley system.  Then we were asked to do the same thing but with the pulley system.  Each method was supposed to use a certain amount of force.  Without the system took 2 N whereas with it should take about 1.0, and for the challenge .5 N.  Attached are the groups results 

Results: How can force be manipulated using a simple machine?
     Since politics have been my focus for the week, I'm going to answer the big question with an government analogy: the relationship between the mass of an object and the amount of force needed to keep it in place is similar to our system of government, with checks and balances.  The less amount of force needed meant you needed to pull on the string more since you can't receive anything for free in a trade off.  

What pattern do you observe regarding the relationship between force and distance in a simple machine?
     The relationship between the two is inverse.  When the force goes up the distance decreases and when the force goes down the distance increases.

New Key Terms:
     (J) for Joules which is the unit for energy.  J= D(distance)xF(force) which is always constant.  

Real Life Example:
Soccer players are the athletes that use natural simple machines the most; the patella

Without this "pulley" the knee joint isn't demolished and the thigh muscles are able to lift the lower leg.  Thanks to this pulley, society is able to enjoy the best sport in the world; soccer.

Mass-Force Lab

• In the first lab of the 2012-2013 school year we were instructed to measure the force from a brass weight.  There multiple brass weights, each with a particular mass.  For the first set of weighing we used a manual probe, and following that was an electric probe.  Once the data was collected, our group formed a graph using the formula y=mx+b to create the line.  The process was repeated, but rather this time with an electric probe.  With both types it was difficult to get an exact measurement because of human error. 
• Once the information was recorded and substituted for variables, we had to figure out what this meant.  After plugging in numbers into the formula the slope was 10 so y=10x+b.  But, there were still three other variables to solve.  X and Y were subbed out for mass and force respectively since they related to the lab.  That left us with B.  After discussing with the group we came to the conclusion that B wasn't necessary because the line passed through the origin.  Compiling all that info together we were able to discover that the gravitational constant on earth is 10 N/kg.  Final Conclusions: an increase of mass means an increase in force, gravitational constant on Earth is 10 N/kg
• Connection to the Real World: This concept is applied in the sport of boxing.  In boxing players are divided up by their weight in order to make the game fair.  For example, 6'4, 220 pound Muhammad Ali would not fight 5'6, 135 pound Manny Pacquiao because Ali produces much more force than the smaller Pacquiao due to his weight.