Can you pleeeeeease answer these physics questions ive tried too but i couldnt its way to hard!!!?

Question

http://www.deena-92.piczo.com
Scroll all the way down to the page and hit on physics these are the questions! PLEASE HELP, i need to revise these questions for an upcoming test

BEST answer will be chosen 10 points !!

hit on enter then the homepage scroll down

this is the exact url http://pic4.piczo.com/deena-92/?g=34705408

Answer 1

First question: The height of the column of mercury above its level in the outer container, 75 cm, allows you to determine air pressure. The pressure of air, pushing down on the mercury on the outer vessel, forces it up the tube. The more pressure, the higher up the tube it goes. You could use the volume of gas trapped above the mercury column too, but it would be harder, and is not the answer they're looking for.

Second one: Cool water descends, hot water ascends. So, if you cool the water at the top of the beaker, it will descend down, creating currents.

Third one: If the room warms up, the air in the bulb at the top expands. The water doesn't expand noticeably, because liquids generally don't. So, the gas in the bulb expands, pushing the water level in the tube below, downwards. A disadvantage of this system is that the water in the beaker will gradually evaporate.

6a: The heat is stored as vibrational motion of the atoms in the metal.

6b: All materials have their own specific heat capacity. This is the amount of energy needed to increase the temperature of 1 kg of the material by 1 degree. The copper heats up more than the aluminium, because it has a smaller value of 'specific heat capacity'.

5. The molecules all just bounce around, at random speeds, in random directions. All their collisions are 'elastic'- meaning that they don't lose any energy when they hit things. Because of this, every surface will have a certain number of molecules crashing into it at any given moment- which is manifested as a pressure.
Heating it up gives the system more energy, so the average speed of the molecules increases, as does their average spacing.
In a gas, there is much more movement of molecules than in the solid. In the solid, they are much closer together, and tend to stay in roughly the same place, relative to each other. ie, a molecule in a solid block, cannot move from one end of the block to the other, but in a gas it can.

Evaporation is a slow process, where occasionally, a few molecules break free of the liquid and form a vapour. Boiling is when the vapour pressure of the liquid is greater than the pressure of the atmosphere. The liquid phase has so much energy that it is all converted into gas.

The latent heat of vaporisation is the energy that goes into breaking the weak bonds between water molecules in the liquid (hydrogen bonds in this case). This energy is all used in breaking these bonds, and not in expanding the liquid, or increasing the speed of the molecules. Since the speed of the molecules is effectively what temperature is, it does not increase.

4c:
120 W is 120 Joules of energy, per second.
0.050 g of water are boiled, per second.
So, 120 Joules, boils 0.050 g of water.
How many joules per gram is this?
120 joules /0.050 g = 2400 joules per gram, which is also
2400 kJ/kg.

Answer 2

Q.1) 75 cms is used to represent the atmospheric pressure

2) Cool the water or liquid at X (top) thus setting up a convection current. Cold water goes down and pushes the warmer liquid to the top which gets cooled and goes down..

5 a) The water level in the tube goes down as the temperature of the room goes up.
b) why? Because the air in the flask expands and pushes the water in the tube.
c) This method is not very sensitive.

6a) the aluminium block stores the heat as increased vibrational energy of the atoms as represented by a higher temperature

The copper block reaches a higher temperature because the specific heat of copper is less than aluminium

I am sorry that I cannot give you the answers to the other questions due to some other work now.

Answer 3

Here are the answers to some of them.I don't have time for the rest.
B 75 cm the greater the atmospheric pressure the taller the column of mercury

Cooling water at X will cause the colder more dense water to sink and force the lighter warmer to rise

5A The water level in the tube will fall below the surface of the water in the beaker

5B Air absorbs heat quicker so as it expands, the pressure in the flask will push the water level in the tube below the surface of the water in the beaker

5C As atmospheric pressure changes, so will the level in the tube.

potential thermal energy

6.2 The specific heat of aluminum is higher. Specific heat is the amount of heat per unit mass required to raise the temperature by one degree Celsius.