9.1 losing heat and braincells

Question 1

Heat is a?

Answer 1

Form of energy

Question 2

Heat flows from

Answer 2

hotter region to colder region

Question 3

What is temperature

Answer 3

Degree of hotness or coldness of object

Question 4

how is temperature measured

Answer 4

thermometer

Question 5

What is diff between heat and temperature

Answer 5

Heat:
Form of energy
Joule (J)
Depends on type + quantity of material & temperature
Temperature:
Degree of hotness / coldness of object
Celsius (`C) / Kelvin (K)
Depends on degree of movement of particles in matter

Question 6

What are three forms of heat flow

Answer 6

Conduction
Convection
Radiation

Question 7

What is conduction

Answer 7

Process of heat transfer from hotter -> colder region through solid
Particles that receive heat energy -> vibrate & collide with each other more frequently -> transfer heat to whole medium

Question 8

What is convetion

Answer 8

Heat transfer by movement of fluid (liquid & gas)

Question 9

What is convection current

Answer 9

Part of fluid that received heat -> expand & less dense -> rise
Colder & more dense fluid -> Downwards
CC = Circulating stream that rises and falls continuously

Question 10

What is radiation

Answer 10

Process of transferring heat without medium
Heat can propogate through empty space & vacuum

Question 11

What effects rate of radiation flow

Answer 11

Type of surface, temperature & total surface area

Question 12

How does heat from Sun reach Earth

Answer 12

Radiation -> propagates through empty space
Penetrates atmosphere -> absorbed by water & land

Question 13

What is an effect of warming of Earth by Sun

Answer 13

Chang in climate
Natural phenomena:
Sea breeze, land breeze, thunderstorm

Question 14

Sea breeze and land breeze is an example of

Answer 14

natural convection process

Question 15

How does sea breeze form

Answer 15

During day, Sun heats up land faster than sea
Warm air on land expands -> less dense -> rise bc lighter
Cold air on sea -> more dense -> draw in to replace warm air on land

Question 16

How does land breeze form

Answer 16

At night, land cools faster than sea
Air above sea -> warmer -> less dense -> rise
Cold & more dense air from land -> move to the sea

Question 17

What are heat conductors

Answer 17

Materials that allow heat flow

Question 18

What is heat conductor in iron?

Answer 18

Base of iron -> metal -> conduct heat -> iron clothes quickly

Question 19

What is heat conductor in bottom of a pan

Answer 19

Made of metal -> allow heat to flow quickly to food

Question 20

What is heat conductor in theromometer

Answer 20

Mercury -> good heat conductor -> detect change in temp very quickly

Question 21

Why isnt water used in thermometer

Answer 21

High adhesion force, water wont come back down

Question 22

Alcohol vs mercury thermometer

Answer 22

Alcohol:
Non toxic - safe
Measure lower temp
Mercury:
Measure higher temp

Question 23

What are heat insulators

Answer 23

Materials that prevent heat flow

Question 24

What is heat insulator in oven gloves

Answer 24

Prevent hands from scald -> taking food try from oven

Question 25

What is heat insulator in cooking utensil

Answer 25

Made of wood -> preventing heat from flowing to hand when cooking

Question 26

What is heat insulator in ice box

Answer 26

Wall -> fibreglass / polystyrene -> maintain coolness of substance

Question 27

When can objects exchange heat energy

Answer 27

When in thermal contact

Question 28

What is thermal equilibrium

Answer 28

No net transfer of heat energy between two objects
Have same temperature