Chapter 10

Question 1

What is the definition of temperature and the SI unit?

Answer 1

Definition: Measure of how hot an object is
SI unit: Kelvin (K)

Question 2

How is temperature measured in?

Answer 2

degree Celsius/degree Fahrenheit

Question 3

Why is our sense of touch inaccurate?

Answer 3

-When both hands are in contact with room tempt water, both register different sensation of degree of hotness/coldness
- Hand earlier in hot water, now feels cooler (becoz now the hand loses heat to the room temperature water-makes it cooler)
- Hand ealier in cold water, not feels warmer (now gains heat from the room temperature water-makes it warmer)

Question 4

How is thermal energy transferred?

Answer 4

• Thermal energy is transferred from the hotter object (of a higher temperature) to the colder object (lower temperature)
• Temperature of colder object increases while temperature of hotter object decreases
• This continues until both objects reach same tempt

Question 5

For heat transfer to occur what MUST be present?

Answer 5

• There must be a temperature difference between 2 objects

Question 6

What happens when an object gains thermal energy?

Answer 6

• Atoms starts to move further apart
• The increase in distance between atoms cause the object to move further apart—expand
• Can occur for all 3 states of matter: solid, liquid, gas
  **ONLY DISTANCE CHANGES NOT SIZE OF ATOMS

Question 6

What happens when an object loses heat?

Answer 6

• Atoms start to vibrate slower and move closer together
• The decrease in distance between atoms causes object to occupy less space—contract
• Can occur for all 3 states of matter: solid, liquid, gas
  **ONLY DISTANCE CHANGES NOT SIZE OF ATOMS

Gas contracts/expands the most
Solid contracts/expands the least
WHY GAS :(
> forces of attraction between gas molecules are the weakest
> easily seperate molecule further apart

Question 7

Another example of expansion and contraction in daily life (NOT RAILWAY TRACK)

Answer 7

• In hot weather, concrete bridge expands
• In cool weather bridge contracts
• expansion and contraction may cause damage
• expansion joins between concrete slabs provide space for expansion
• rollers under bridges allow expansion and contraction to take place safely

Question 7

an example of expansion and contraction in daily life

Answer 7

• in hot weather, metal railway tracks gains heat and expands
• track buckle if it is made in one continuous metal piece.
  (cause- trains to derail)
• expansion gaps between railway tracks provide space for expansion

Question 8

An example of expansion and contraction in climate change

Answer 8

• oceans absorb more than 90% of thermal energy in Earth’s atmosphere.
• Thermal energy is needed for oceans to maintain suitable temperature - support marine life

Question 9

What happens when oceans get overheated?

Answer 9

• Climate change includes- global warming- results in oceans absorbing more thermal energy. - Causes oceans to expand and sea level to rise
• Rise in sea level causes more coastal land to be washed away. Coastal erosion-increases

Question 10

If lid is too tight to open what should be done?

Answer 10

• Place it in hot water as metal expands more than glass jar, this makes lid less tight and easier to unscrew

Question 11

What is a bimetallic strip?

Answer 11

• Made of two different metal strips (e.g. brass and iron)
• When heated/cooled, the flat strip bends because one metal expands/contracts more than the other
  eg: brass expands more than iron when heated, brass contracts more than iron when cooled