184_projects:s21_project_10

Dr. McPaddel woke up to a great surprise this morning when she walked outside to admire the junkyard and noticed a mysterious glowing creature stuck to her magnetic crane. Apparently, in all the excitement of showing the contraption to her neighbors, she had forgotten to turn off the machine. The creature had wandered into the scrapyard overnight looking for some metal to eat, and when it wandered near the crane, the metal became magnetized and pulled the creature up into the air, where it remained stuck until Dr. McPaddel discovered it this morning. She alerted the authorities, but it was the Hawkion researchers who arrived before anyone else, to transport the creature to a research facility to learn more about it. They are thinking these animals might be responsible for the disappearance of fish from the lake and green-bellied canaries from the cliffside.

By the time you learn of all this, the creature is already at the research facility. You arrive and the scientists fill you in. They have acquired this beast to study it, but by now they have figured out Dr. McPaddel's crane snagged a young version of the monster. Because of the apparent resemblance to both boars and tigers and their electromagnetic glow the scientists at the compound have taken to calling the monsters EM-boar tigers. So you have captured an EM-boar tiger cub. It turns out that EM boar tigers are super protective of their young and they have organized to attack the Lakeview compound. Surprisingly, even though it is a government facility, there are no guns at the compound. But you are scientists and engineers godammit! You indicate that maybe capturing this new 'alien' species young might have upset the creatures and make a plan to return the beast but you need a distraction to get the cub close enough to give back to its kin.

You decide to construct makeshift launcher that is using magnetic force to launch projectiles so that they will leave the launcher at a speed of $300m/s$. You must construct your launcher on the floor of the laboratory and position it at an angle of 63 degrees so that it is firing out of the window of the laboratory.

At your disposal to construct your launcher, you have access to two copper rails that can be cut to your specifications. You also have perspex that you can cut to any dimensions and chunks of aluminum that can be cut to any shape. You also have access to multiple variable power supplies that can be set to a requested current and a bunch of wires that can be cut to any length and some switches. You must outline your design, explaining the physics behind the design of the magnetic force launcher and indicating the current needed to reach an exit velocity from the launcher of $300m/s$.

caged.jpg

Learning Goals

  • Understand how superposition of magnetic fields works and practice adding magnetic fields together
  • Relate magnetic fields to forces and use those forces to calculate motion
  • Review some basic kinematics concepts - net force, acceleration, velocity relationships
  • Find the net force on an object & draw a free body diagram
  • Practice building complex models using assumptions and approximations to simplify

You are able to use your successfully MacGyver'd metal detector to track what the EM-boar tigers have left behind and find your trapped team members. But it is not only your team members you find. It is the EM-boar tigers base of operations. More important than rescuing your team members you observed something in their lair that effects the whole of humanity and needs to be communicated immediately. You estimate there is about 1 hour and 50 minutes to figure out a way to send some sort of E&M signal out for rescue before the EM-boar tigers realize that you are planning an escape. (What will that signal be??? You decide.) Due to the sensitivity that EM-boar tigers have to E&M waves, you only have one chance to send the signal before they realize what is happening and close in on the team. You will need to make sure that the attempt will work. You have a small metal ball that can be charged up 1e-6 C without discharging in air. You've found a piston that can shake the ball a total distance of 2cm, but at nearly any frequency you need. Your team decides to create a model of the signal to determine how best to orient the setup, how much charge to dump on the ball, and how quickly to shake it. Your group has already started setting up the code.

GlowScript 2.6 VPython

## Objects

charge = sphere(pos = vector(0,0,0), radius = 0.001)
charge.v = vector(0,0,0)

## Constants and model parameters

q = 1e-6
k = 9e9
mu = 4*pi*1e-7
mofpi = mu/(4*pi)

## Set up time parameters

t = 0
dt = 0.1


## Create list of arrows that encricle the charge
## Each location has two arrows: one for E and one for B

N = 20
theta = 0
dtheta = 2*pi/N
R = 0.02
ArrowList = []

while theta < 2*pi:
    
    Loc = vector(R*cos(theta), R*sin(theta), 0)
    
    ArrowList.append([arrow(pos=Loc, axis = vector(0,0,0), color=color.cyan),arrow(pos=Loc, axis = vector(0,0,0), color=color.magenta)])
    
    theta += dtheta

## Calculation loop

while t < 1000:
    
    rate(100)
    
    ## Charge should oscillate
    
    
    ## Loop through arrows to make E and B vectors
    
    for Arrow in ArrowList:
        
        r = Arrow[0].pos - charge.pos

        E = vector(0,0,0)
        B = vector(0,0,0)

        Arrow[0].axis = E
        Arrow[1].axis = B
       
    t = t + dt

Learning Goals

  • Make predictions for the electric and magnetic fields from a moving charge over time
  • Model (using VPython/Glowscript) the electric and magnetic fields from an oscillating charge
  • Explain the effect of changing a variable on your model of the electric and magnetic fields (i.e., what would you expect to change if you changed the magnitude or sign of the charge)
  • 184_projects/s21_project_10.txt
  • Last modified: 2021/04/07 16:42
  • by waterso8