The Top Ten Applications of Physics While Camping

Part of the reason physics is so phun is we can see it all around us.  I noticed physics this weekend, camping in the Great Smokey Mountain National Forrest. I also got 43 bug bites.  Below are the "The Top Ten Applications of Physics While Camping", organized by unit for simplicity.

Unit One: Velocity

1.  To get to the forrest, we had to drive about an hour.  The road was windy, and the speed limit changed often.  These two things meant that we were never traveling with constant velocity or acceleration, because both our direction and speed were changing almost constantly.

Unit Two: Newton's Second Law

2.  Newton's second law states that acceleration is directly proportional to force and inversely proportional to mass.  This was evident this weekend when we were skipping rocks in the stream by our campsite. The harder we threw the rocks, the faster they went, while lightly tossing rocks did not make them go as far.  Similarly, we could see this in the size of the rock.  The lighter rocks went faster than the heaver rocks.

Unit Three: Newton's Third Law

3.  We saw Newton's Third Law when we were hiking.  The 3rd law states that every action has an equal and opposite reaction.  When hiking up a step hill, just as we push the ground backwards, the ground pushes us forward.  However, we pushed the ground harder that the ground pushed us; this was the reason that we were able to climb the hill.

4.   Although our camping trip only involved hiking, some camping trips require rock climbing.  For rock climbing, nylon ropes are used instead of cotton or wool ropes.  This is because when a climber is falling, they will go from start to stop, no matter the surface they are landing on.  This change in momentum (p=mv) is represented by the equation ∆ p= p final - p initial, and is the same no matter the surface they are landing on.  Since the ∆ p is constant, and we know that ∆ p=J, we know J is also constant.  Since J is the same, the rope will increase the amount of time taken to stop as a result of the bounce.   An increase in time means a decrease in force.  More time=less force=safe landing.

Unit Four: Rotation

5.  Camping requires a lot of materials, and if you're backpacking, that can mean carrying a heavy pack.  If you're not balanced, a heavy pack can cause you to fall over-- what a disaster!  This disaster may occur as a result of torque (force x lever arm).  If your body's center of gravity is too high or off center, there could be a torque, causing you to fall.  For this reason, backpackers must widen their stance, thus widening their base of support.  This allows for the center of gravity to be over the base, greatly decreasing the likelihood of falling over because of a heavy backpack.

Unit Five: Work and Energy

6.  Closely related to hiking and camping in a literal sense, work and power are also related with Physics!  We can see machines, a tool that reduces the FORCE of an object (not its energy or work) in bear hangs, used to get food and toiletries out of a bear's reach.  At well established campsites, often park rangers will construct bear hangs with pulley systems, like shown below.  Pulleys are a form of machine that reverse the direction of the force you are applying.  This greatly decreases the amount of force, making the work (work= force x distance) easier.

Unit Six: Charges and Electricity

7.  Perhaps one of the most obvious needs while camping is a flashlight or headlamp. It was great learning about how batteries and lightbulbs worked, so that I could transfer that knowledge to my fellow campers.  Batteries use DC or direct current, meaning that the current flows in one direction from the high energy end to the low energy end.  When connected with a current carrying wire to a lightbulb, the circuit causes current to run thru the bulb, lighting the flashlight.  Who knew Physics made it possible to see at night out in the woods?!

8.  A not so fun part of camping is the threat of rain, specifically thunderstorms.  Lightening occurs when clouds in the sky rub together, and become charged thru friction.  This causes the top of the cloud to become slightly positive and the bottom to become slightly negative.  The ground then becomes slightly positive thru induction from the negative part of the clouds.  Since opposite charges attract, the positive charges in the ground start to creep up towards the negative charges in the clouds.  If the path is completed, energy is released in the form of sound (thunder), heat, and light.  

Unit Seven: Magnetism

9.  After a great weekend camping, we had to return to campus.  This required a second hour-long drive in the car, which is also powered by Physics!  Motors in cars, although more complex, rely on the same basic principles to work as the simple motors we worked on in class.  Motors require only two things: a magnet and a current carrying wire.  To work, motors rely on the torque felt by the current carrying wire's moving charges.  This force causes a torque, which spins the motor.  Motors convert electrical energy to mechanical energy, and are necessary to working cars.

10.  On the drive home, campers will undoubtedly pass a stoplight. The sensors that tell the traffic light when a car is waiting also has Physics to thank.  In this case, electromagnetic induction is our hero! Under the road, there are coils of current carrying wire.  When a car, essentially a giant magnet, passes over the wire, it changes the magnetic field of the wire.  This change in magnetic field induces a voltage, which causes a current, which acts as a signal to the traffic light.  Without electromagnetic induction, the smelly campers would be waiting forever!

So that is the The Top Ten Applications of Physics While Camping.  Although the bug bites and sun burns might fade, the memories and and physics lessons learned certainly will not.

Signing off for my last blog post-

Annie

Go Blues. Go Camping.  Go Physics.

Wind Turbine Blog

This week and last week, we worked in groups to make Wind Turbines.  In order to understand how wind turbines work, there are a few important "physics phacts" to know.

The wind turbine, although powered by wind, required a generator to induce voltage.  A generator consists of either a coil of wire spinning around magnets or magnets spinning around a coil of wire.  We choose to do the latter, as it is technically more simple.

Generators work as a result of Electromagnetic Induction, wherein the magnetic field of a coil of wire is changed as a magnet passes over it.

As far as our design goes, we modeled our generator from this website.  From the website, we knew we needed to purchase ceramic block magnets and a metal rod.  The red of the materials we were able to find in the classroom.

The turbine was not apart of the generator tutorial, so Claire and Holt took charge of the design.  We had initially planed to use wooden boards as the blades, but found that cut-up plastic bottles were also good to use.  In oder to make them spin, we had to tweak the angles of the blades, the directions, and the direction the wind was coming from.

The coils of the wire allow the current to flow.  It was important to note the direction of the wire's current, which is why you can see green arrows marked on the box.

The magnets, shown to the left inside the box, are what causes the change in magnetic field in the wire.  The metal rod is spun by the wind blades, which in turn spins the magnet.  The movement causes the generator to work.

Here is out wind turbine working!

In the end, we generated 0.008A of Current and .005V of Voltage.  Despite this very impressive result, we were unable to light the lightbulb because of the friction from our magnet.

Although significantly less stressful than the mousetrap car, this project did have its challenges.  Specifically, the copper wire.  Somehow, it became tangled, and made our lives very difficult.  In the future, I would work more carefully to ensure it did not become tangled.

As I mentioned above, we also learned the importance of trial and error in relation to the wind turbine blades.  Being able to adjust and readjust them depending on our needs became very important.

A huge lesson would also be to label the poles of the magnets.  Otherwise, you just might have to force two like poles together, which is not an easy task.

From this, I have learned how a generator works! I have also learned just how exact and frictionless it must be to produce a voltage, and not only that, but also a strong enough voltage to light a lightbulb.

Unit 7 Summary

In Unit 7, we focused on Magnetism.

The first topic of discussion was Magnetic Fields.  Magnetic fields are created by moving charges, and have a symbol of 'b'. Field lines travel from the South to the North pole inside the magnet, and from the North to the South pole around the magnet.  Magnetic fields are 3D.

Magnetic fields are the reason that like poles repel and opposite poles attract. When magnetic field lines are going in different directions, the magnets repel, but when the magnetic field lines are facing the same direction, the magnets attract.

Magnetic fields are also what allows a paperclip to stick to a magnet.  Before coming into contact with a magnet, a paperclip's domains (random clusters of charges all moving in the same direction) are unaligned.  When brought near a permanent magnet, the magnet's b causes the paperclip's domains to align along with the magnet's b.  The paperclip is now a magnet with its own North and South poles and magnetic field.  Because opposite poles attract, the paper clip sticks to the magnet.  

The Earth's magnetic field is interesting in that although geographic North is Canada, that region is home to the magnetic South.  Thus, the magnetic field runs from Canada (the magnetic South) to Antartica (the magnetic North) inside the Earth, and from Antartica back to Canada outside of the Earth.  This is the reason that the Northern Lights occur.  Cosmic rays can only enter the atmosphere when moving parallel to the Earth's magnetic field.  Should the cosmic rays attempt to enter the atmosphere at the equator, the Earth's b would deflect them back into space.

The last, and perhaps most obvious, part of magnetic fields are Compasses. A compass is simply a magnet that is free to move, and aligns with the direction of the magnetic field.

Below is a podcast made by yours truly about Magnetism.

The next topic was Forces on Charged Particles.  

The most important thing to remember is the Right Hand Rule.  Just like in the diagram, the thumb shows the direction of the force, the index finger shows the direction of the current, and the middle finger shows the direction of the magnetic field.  

Also in the realm of Forces on Charged Particles are Motors.  Motors consist of current carrying wire and a magnet.  They convert electrical energy into mechanical energy when the current carrying wire feels a force caused by the moving charges.  This force creates a torque, making the motor run.  For more on motors, check out my motor blog here. 

Finally we discussed Electromagnetic Induction.  This occurs when there is a change in the magnetic field of a loop of wire, and voltage is induced, which, in turn, causes a current.  This is seen again and again in our crazy, modern world, like in credit card machines, traffic lights, and metal detectors.  

Electromagnetic Induction also allows transformers to work. A transformer is a box with two coils of wire that can either increase or decrease voltage into an appliance. They work by changing the magnetic field of the primary coil through AC, which means that the b is constantly moving and changing.  This then changes the magnetic field of the secondary coil, which changes the voltage.  

Faraday's Law shows us that:

Transformers can be found on power lines, computer chargers, and appliance plugs.  

Generators also work because of Electromagnetic Induction.  Like a motor, they require a loop of wire and a magnet.  However, this is where the similarities stop.  Generators convert mechanical energy into electrical energy, and in this case, either the magnets are moving around the wire or the wire is moving around a magnet.