lab8 march19(electric charge and force)

Activity scotch tape strips

a. You and your partner should each place a 10 cm or so strip of Scotch tape on the lab table with the sticky side down.  The end of each tape should be curled over to make a non-stick handle.  Peel your tape off the table and bring the non-sticky side of the tape toward your partner’s strip.  What happens?  

We find the two stips repel each other

b. Place two strips of tape on the table sticky side down and label them “B” for bottom.  Press another strip of tape on top of each of the B pieces;  label these strips “T” for top.  Pull each pair of strips off the table.  Then pull the top and bottom strips apart.

1.We find they attract each other.for two top strip

2.we find they repel each other for bottom

3. a top and a bottom slightly attract

By using logger pro, we solve a problem finding the E force on the ball

force vs distance

Theses are our analysis for the force on the ball. 

Then, we are introduced to Coulomb’s Law and solve problems for two charges.

This is a machine which can generate a lot of charges. What will happen if the metal plate is put on top of it after turning on? The metal plate drift off the table because they have same charges.Thus, they repel each other

This is a problem on electrical force. We have to use vectors and determine the sign for each force. if they attract, the force direction is pointing to the left. otherwise, it points to the right.

lab9 march24 (electrical fields)

We are introduced to superposition principles in electrical filed. E=E1+E2+E3....En
Then we deduct the electrical field formula.using vectors

By using Vpython, we can draw the electrical field lines on computer.

This is the code. We scale it many times until we find the proper scalefactor

Then, we solve a problem for two electrical charge generating electrical field on a point

Given a charge density for a long rod, what will be the electrical field it generated?

Using integral, we find the answer regarding to d, L

The goal of this section of the activity guide is to calculate the electric field 

 corresponding to a continuous charge distribution on a rod at two points in space, P and P', as shown below.

Then, we solve this problem using excel by increment the L each time, we calculate new r and find the E total. since it is parallel to the z axis, the final answer is only on the y axis.

lab 10 march 26( Dipole moments and Electric Flux )

2 electrical charges in an field will point tot eh opposite direction and the net force on dipole is 0.

torque=2Fsin(theta)=2qEsin(theta)=PEsin(theta)=PxE(vectors cross product)

Then using integral find change in potential energy.

U2-U1=PE(cos(theta1)=cos(theta2))

draw the electrical field lines on the board.

Then we use Vpython to draw the electrical field lines.

Flux=Acos(theta)kq/r^2=EAcos(theta)

m^2 N/C

 open space:

flux=E.A(dot product)

closed space

flux=integral of E.dA(vectors)

Below is a question, finding eh flux within the rectangular box. what will be the flux total? left side and right side cancel out, The answer is 0

VPython tutorial

2,
3D Objects
create 3 balls with vectors sticked on it and pointing toward a certain direction

from visual import*

##3 balls

sphere(pos=vector(0,-5,0),raduis=1,color=color.green)
arrow(pos=vector(0,-5,0),axis=vector(+3,+3,0),color=color.red)

sphere(pos=vector(5,5,0),raduis=1,color=color.green)
arrow(pos=vector(5,5,0),axis=vector(-5,0,0),color=color.red)

sphere(pos=vector(-5,5,0),raduis=1,color=color.green)
arrow(pos=vector(-5,5,0),axis=vector(0,-3,0),color=color.red)

4. after watching variable assignment, create 3 balls with vectors connecting  balls

from visual import*

##vectors2

b=sphere(pos=vector(0,-10,0),raduis=3,color=color.green)
c=sphere(pos=vector(5,5,0),raduis=3,color=color.green)
a=sphere(pos=vector(-5,5,0),raduis=3,color=color.green)


arrow(pos=b.pos,axis=c.pos-b.pos,color=color.red)
arrow(pos=c.pos,axis=a.pos-c.pos,color=color.red)
arrow(pos=a.pos,axis=b.pos-a.pos,color=color.red)

4. **move one sphere twice as far from the y-axis.

4.1 Print command

from visual import*

b=sphere(pos=vector(0,-10,0),raduis=5,color=color.green)

c=sphere(pos=vector(5,5,0),raduis=5,color=color.green)

a=sphere(pos=vector(-5,5,0),raduis=5,color=color.green)

arrow(pos=b.pos,axis=c.pos-b.pos,color=color.red)

arrow(pos=c.pos,axis=a.pos-c.pos,color=color.red)

arrow(pos=a.pos,axis=b.pos-a.pos,color=color.red)

print(a.pos) 

The following lines show in the shell:

Python 2.7.9 (default, Dec 10 2014, 12:28:03) [MSC v.1500 64 bit (AMD64)] on win32

Type "copyright", "credits" or "license()" for more information.

>>> ================================ RESTART ================================

>>> 

>>> ================================ RESTART ================================

>>> 

>>> ================================ RESTART ================================

>>> 

<-5, 5, 0>

lab 7 March17(entropy and cycles)

If we throw them in the air, what will happen? We will see flying purple pepes leader. 

We are introduced to diesel engine, 

We add heat to ices melting, but the temperature does not change , why? 

We learn how 4 stroke works and called for each step on PV diagram.There are different cycles. diesel cycle, stirling cycle, brayton cycle.

Then, we solve problem for heat pump and effectiveness of refrigerator.

Professor Mason demonstrated how bubbles generated by blowing air inside the tube, and how does it look when we set fire on bubbles.

lab 6 March12(entropy and cycles)

A thermal cooler which is shown below, has one end in the hot water, and the other end in the cold water. We assume the spinning direction will reverse if we switch the two ends. It is proved to be right.  By putting one end on the electric charge, we get the same result.

We deduct the molar heat capacity Cv and Cp at constant heat. 

Then, we deduct useful formula for ithothermal process.

We solve a problem using the property of ithothermal.

Then, we solve problem carnot cycle.

Then, we are introduced how 4 stroke cycle works

EXHAUST STROKE 

We discuss how to increase the power ouput by increasing volume, revelvtions and pressure