chap 9

Question 1

Heat is a form of

Answer 1

energy

Question 2

heat flows from a:

Answer 2

hotter region to a colder region

Question 3

what does temperature mean

Answer 3

• a measure of the degree of hotness or coldness of an object

Question 4

State a few characteristics of heat that makes it different from temperature

Answer 4

heat:
- form of energy
-measured in joule (J)
- amount of heat depends on the type of material, quantity of material & temp

Question 5

State a few characteristics of temperature that makes it different from heat

Answer 5

temperature:
-the degree of hotness or coldness of an object
- measured in degree celsius (C) or kelvin (K)
- depends on the degree of movement of the particles in a matter

Question 6

Heat flow happens in 3 ways:

Answer 6

• conduction
  -convection
  -radiation

Question 7

Elaborate on conduction

Answer 7

• process of heat transfer frm hotter regions to colder regions through a solid medium
• particles that receive heat energy will vibrate and collide more frequently and transfer the heat to the whole medium

Question 8

elaborate abt convection

Answer 8

• heat is transferred by the movement fluid (liquid gas) from hotter regions to colder regions
• part of the fluid that receives heat will expand, become less dense and rise
• colder n more dense fluid moves downwards
• circulating stream that rises and falls continuously is known as convection current

Question 9

elaborate about radiation

Answer 9

• process of transferring heat without any medium
• heat can propagate through an empty space or vacuum
• the types of surface, temp and total surface area of an object will influence the rate of heat flow

Question 10

heat energy frm the sun is transferred to the earth through

Answer 10

radiation

Question 11

The warming of the earth by the sun causes changes in climate and the occurrence of natural phenomena such as:

Answer 11

sea breeze, land breeze, thunderstorms

Question 12

Elaborate abt sea breeze

Answer 12

• formation of land breeze and sea breeze r examples of a natural convection process
• Sun heats up the land faster than sea during the day
• warm air on land expands, becomes less dense and rises bcuz its lighter
• cold air from surface of the sea that is more dense is drawn in to replace the warm air on land n results in sea breeze

Question 13

elaborate on land breeze

Answer 13

• land cools faster than the sea at night
• air above sea which is warmer becomes less dense n rises
• the cold n more dense air from land begins to move the sea resulting in land breeze

Question 14

Head conductors are

Answer 14

Materials that allow heat flow

Question 15

Heat insulators are

Answer 15

materials that prevent heat flow

Question 16

two objects which are in thermal contact can :

Answer 16

exchange heat energy between them

Question 17

when there is no net transfer of heat energy between the objects, the objects are said to be in:

Answer 17

thermal equilibrium

Question 18

two objects that are in thermal equilibrium have:

Answer 18

the same temperature

Question 19

Explain how heat effects solids

Answer 19

• particles in a solid vibrate at a fixed position
• the particles vibrate faster n move further apart when heated
• this causes the volume of the solid to increase bcuz the solid expands
• particles vibrate slower n move closer when cooled
• causes the volume to decrease bcuz solid contracts

Question 20

explain how heat effects liquid and gas

Answer 20

• particles in liquid and gas move freely
• the particles move faster n randomly n the distance between them increases when heated
• causes the volume of liquid n the gas to increase bcuz the liquid n gas expand

Question 21

Name some uses of expansion n contraction of matter in daily life

Answer 21

• thermometer
• steel bridges
• railway tracks
• bimetallic strip

Question 22

The ability of an object to absorb or radiate heat depends on the:

Answer 22

type and colour of its surface

Question 23

when an object radiates heat, its:

Answer 23

temperature decreases