4th 6 weeks physics BRs

Bell ringer 1/23In a steam turbine that is used to drive an electrical

generator, hot steam flows from one end of a tube to another, cooler end. As the steam flows, it turns the turbine, increasing the kinetic energy. Because of the laws of thermodynamics, which must be true about this system?

A. Only some of the heat energy is converted to kinetic energy.

B. Output kinetic energy is greater than input heat energy.

C. Some energy is destroyed during transformation.D. The total energy of the system increases over

time.

Bell ringer 1/24Draw and label a bohr model of an atom.

Label charges as well.

BELL – RINGER 1/311.Suppose two balloons

hanging from strings repel one another. What are the possible charges for the balloons? Draw a free-body force diagram for the balloons.

Bell – Ringer 2/5What are electric field lines?Where have you seen these before?How do electric field lines look around a

positive charge?How do electric field lines look around a

negative charge?

Bell-Ringer 2/6How do we determine if the force between two charges will be attractive or repulsive?

2/19/13What type of force is present between a tiger

and a rock each with a different mass?ElectrostaticGravitationalRepulsiveAll of the above

3-1-13 Bell-Ringer:What is an Electromagnet?

Have you ever heard this word used before? If so, how and where?

Bell-Ringer 3-6-13Yes you have to DRAW it!

1. What is the voltage?2. What is the current?3. If the voltage were increased to 40V, what would

the current be?

Bell-Ringer 3-7-13Use your devices (AKA phones n’ stuff)! You may use a partner if you have no internet.

1. What does a transformer do?2. How do the magnetic stripes on credit cards

work?3. If gold is a better conductor than copper, why

don’t we use gold to wire our homes?4. Why is electricity dangerous?

a. High voltageb. High resistancec. High currentd. All of the above

Answers1. A transformer transfers current from on

circuit to another and lowers voltage delivered to the home.

2. Little bits of iron (magnet) in the strip are correlated to numbers allowing the card reader to interpret the data electronically.

3. Thievery! It also happens with copper now since its value has increased.

4. C. Because potential difference creates current!

Bell-ringer 3-191. A long wavelength indicates a

______ frequency, and a short wavelength indicates a _______ frequency.

2. Can we see all electromagnetic waves? Which electromagnetic waves can we see?

Bell-Ringer 3-20Write the following questions and leave space between each:

What materials did you use to make your wave machine?

How long is your wave machine?How long does it take for your wave to return

back to the original point of disturbance? (Do three trials)

Bell-Ringer 3/21Trial Do distance/time to see how

long it took your wave machine to travel back and forth.

Trial #1

Trial #2

Trial #3

Bell-ringer 3-25What are some wave interactions we have discussed in class? (at least two)

Bell-Ringer 4/1Suppose a whistle has a frequency of 325Hz and the whistle maker knows the length of the whistle should be ¼ the wavelength. The speed of sound is 343m/s. How long should the whistle be?

Bell-Ringer 4/9Using addition, how many ways can you have

a sum of eight using two whole, positive integers? List all.

Bell-ringer 4/10Name 4 elements that are likely to bond with

Fluorine.Which list of elements share similar chemical

properties.?a) Li, Be, Ca, Ob) O, Cl, P, Nc) H, Na, K, Frd) B,C,N,O

Bell-ringer 4/11

Bell-Ringer 4/12

Bell-Ringer 4/15Write the chemical formula for

Beryllium NitridePotassium SelenideBarium ChlorideLithium Iodide