__________________________________________1Kismet_________________________________________

Monday, July 19, 2010

SHort revision for physics test ._. @ 9:31 PM

Hey people! Here is a short revision for the physics Theory test! Ya’ll can just read through. Some are a repeat from the Notes for Practical Test Notes posted previously ._.

Definitions

1. Molecular Kinetic Energy: depends on speed of M

· Temperature high = M expand = speed of M increase

2. Molecular Potential energy: depends on intermolecular distance

· Further M are from each other= higher MPE

· Due to attractive forces between particles

3. Internal energy = MKE + MPE

· More molecules more mass = more IE

4. Temperature: measure of degree of hotness/coldness relative to a standard scale

· Measure AVERAGE Kinetic energy

· SI unit = Kelvin

5.Thermal Energy: Energy-in-transit that is being transferred from a region of higher to lower Temperature

6. Heat: Active transfer of thermal energy from a hotter body to colder body due to TEMPERATURE DIFFERENCE

7. K = C +273

8. Physical Property = Thing that can be measured

9. Thermometric property = A physical property that changes continuously with temperature

10. Memorise Table on Page 3 off 11 in Notes

11. Steam Point = Temp. of steam from boiling water at a pressure of one standard atmosphere.

12. Ice Point = Temp. of PURE melting ice at the pressure of one standard atmosphere.

Things to know

1.Steam point and Ice point CANNOT be changed.

2. Differences between Alcohol & Mercury

Property	Mercury	Alcohol	Advantage/ Disadvantage
Colour	Silver	Transparent	Alcohol cannot be seen and needs to be dyed. (Change boiling point/ Melting point due to impurity)
Freezing point	-39 DC	-115 DC	Alcohol can measure lower temp.
Boiling Point	357 DC	78 DC	Mercury can measure higher temp.
T conductivity	High	Low	Mercury more responsive
T expansivity	Low	High	Alochol more sensitive
Adhesion to glass?	Does not stick	Stick to glass	Mercury gives a more reliable reading.
Uniform expansivity?	Uniform	Not uniform	Mercury gives a more reliable reading.

3. 3 main characteristics of Thermometers:

· Responsiveness : How QUICKLY it changes

· Sensitivity: How MUCH it changes

· Range: How much it can MEASURE

4. Read up pg 146 of the Physics TB

5. Clinical Thermometer:

· Measure 35 DC to 42 DC. Narrow constriction to prevent liquid from flowing back into the bulb to allow time for measurement

· Cross-section is pear-shaped to magnify the liquid

If…increases	Sensitivity	Responsiveness	Range
Thickness of wall of glass bulb	-	Decrease	-
Size of bulb	Increase	Increase	Decrease
Length of Capillary Tube	-	-	Increase
Capillary bore size	Decrease	-	Increase
T Expansivity	Increase	-	Decrease
T Conductivity	-	Increase	-

7. Lowest Possible Temperature = Absolute Zero

· All thermal energy is transferred away from body

· Particles have minimum energy and movin gat slowest speed

8. Boiling point increase when you add pressure or impurities

9. Melting point decrease when you add pressure or impurities.

· If the MP of Ice was 0 DC, then when impurities/ pressure is added, the MP will decrease to perhaps -3 DC. Then, at 0 DC the ice will become water. And ONLY at -3DC or below it will become Ice.

How Scientists Work

1. Remember to read measurements with EYE LEVEL at the TOP OF MENISCUS of the Thermometer.

2. If an experiment involves putting a thermometer in blah blah and such, make sure the following words appear in your procedure:

· Place thermometer VERTICALLY using the clamp

· Record the STEADY temperature

3. Remember the 3 types of Variables:

· Independent: Intentionally changed

· Dependent: Factor that might be affected by IV

· Constant

4. Type of Observations:

· Qualitative: describe

· Quantitative: Measure

FAQ

1. Explain why you feel colder when you enter an air-con rm after a hot bath as compared to when you enter a rm at rm temp.

· The TEMPERATURE of the air-con rm is lower than the rm at rm temp.

· The body after a hot bath will have a HIGHER EXTERNAL BODY TEMP.

· The body's temperature difference with the rm at rm temp. is smaller as compared to the air-con rm and thermal energy transfer is smaller.

· When thermal energy transfer is faster, the body will feel colder.

2. Is the sense of touch a good way to measure temp. of an object accurately? Why?

· No. Detect a range of temperature only.

3. Why is the skin not a good sensor of temp.?

· Will determine a wrong range when the skin if affected by a previous object after measuring

4. What makes a good thermometer?

· Easy-to-read scale

· Responsive & Sensitive to slight temp. changes

· Able to measure a wide range

5. Why clinical thermo. Has a short range?

· Designed to measure body temp. which stays at about 36.9 DC.

6. Why clinical thermo. cannot measure rm temp.?

· Rang of rm temp. is 28 DC to 35 DC.

7. Why ice shavings are used instead of ice cubes when measuring melting point of ice?

· Ensure good thermal contact w/ e bulb

· Result will be accurate.

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