Answer:
Areas where the rocks have a reversed polarity
Explanation:
The rocks are an excellent natural indicator about the past of the magnetic field of the Earth and its changes. This is due to the direction of the metallic crystals, which always point toward the strongest pole. While in the present, the North Pole is the one that has the stronger magnetic field, it has not been like that always in the past, but there has been periods when the South Pole has been the stronger one. This can be seen by some rock samples found in the oceans, as their crystals are pointing toward what is now the South Pole, not as the newer rocks that point toward the stronger North Pole, meaning that the South Pole had the stronger magnetic field in certain periods of the past, which can be determined by the age of the rocks.
Answer:
15.3 sorry if i got it wrong
Explanation:
Let us first calculate heat obtained by the evaporation of 51 g of water.
Given, heat of vaporization of water = 2.4 kJ/ g
∴ Heat obtained by evaporation of 51 g of water = 2.4 × 51 = 122.4 kJ
This is the heat energy available that can be used to cool water from 42°C to 20°C.
Specific heat of water is given by,
Here,
C is the specific heat of water = 4.18 J/gK
Q is the amount of heat = 122400 J
m is the mass of the water that can be cooled.
dt is the change in temperature= 42°C ₋ 20°C = 22°C ( The numerical value will be the same if Kelvin unit is used.)
Substituting the values we get,
m = 1331 g
1331 grams of water can be cooled from 42°C to 20°C by evaporation of 51 g of water.
Answer:
Explanation:
When the cold milk is added into the hot coffee, heat is transferred from the coffee (higher temperature) to the milk (lower temperature), until the two substances are at the same temperature (thermal equilibrium).
Therefore, the heat given off by the coffee is equal to the heat absorbed by the milk; so, we can write:
where:
is the mass of coffee
is the specific heat capacity of coffee
is the initial temperature of the coffee
is the mass of milk
is the specific heat capacity of milk
is the initial temperature of milk
is the temperature at equilibrium
Solving for , we find the final temperature of the coffee at equilibrium: