For the 2011 Common Test 3 question 15d and 15e, I'm not clear about why potential energy is greater in B than in A. As there is limited movement in A so doesn't that mean it is storing more energy?
Potential energy of molecules depends on the spacing (or separation) between molecules.
In B, molecules are further apart, so more p.e. in these molecules in this state.
Movement, or more specifically speed, is related to kinetic energy of molecules.
Hi Mr Ang, to boil a beaker of water, must we open or close the air hole of the bunsen burner to obtain a luminous or non-luminous flame? Can u explain to me the difference and function of luminous or non-luminous flame?
The change in melting point just changes the temperature at which a substances turns from solid into a liquid state. The packing of molecules would just be related to the state of the substance at any time/temperature.
When item A is said to be at a higher temperature then item B, this means that item A has more internal energy than item B? or Item A loses heat energy to item B when they are in contact?
1. higher temperature only means higher average kinetic energy of molecules in a substance.
If A and B are of different substances, their p.e. of molecules would be different since spacing would be different due to the nature of the substance, how the molecules are arranged. Other factors that also affect the internal energy include: mass of each item, state of each item,
2. If A and B are in contact, yes, A loses heat to B, as heat flows from region of higher temperature to a region of lower temperature. This heat transfer stops when A and B reach the same temperature.
Mr Ang, if they ask us: when body X is said to be at a higher temperature than body Y, this means that...
a)body X has more internal energy than body Y
b)body X loses heat energy to body Y when they are in contact
the answer is b. why isn't it a?
thanks
Temperature gives an indication of the average k.e. of molecules (but mass will also affect the total k.e. of molecules)
Internal energy = k.e. + p.e. of molecules, but there is no information to compare the p.e. of molecules.
You don't have permission to comment on this page.
Comments (16)
Claudia Chen said
at 10:33 am on Sep 22, 2011
For the 2011 Common Test 3 question 15d and 15e, I'm not clear about why potential energy is greater in B than in A. As there is limited movement in A so doesn't that mean it is storing more energy?
johnlittlephysics said
at 8:00 am on Oct 5, 2011
Potential energy of molecules depends on the spacing (or separation) between molecules.
In B, molecules are further apart, so more p.e. in these molecules in this state.
Movement, or more specifically speed, is related to kinetic energy of molecules.
Pang Seok Mun said
at 9:07 pm on Oct 4, 2011
Hi Mr Ang, to boil a beaker of water, must we open or close the air hole of the bunsen burner to obtain a luminous or non-luminous flame? Can u explain to me the difference and function of luminous or non-luminous flame?
johnlittlephysics said
at 7:57 am on Oct 5, 2011
To boil water, use the hottest flame from a non-luminous flame (faint blue), with air hole open, such that more oxygen available for effective burning of gas, hence much heat is released.
See more details at
Ref: http://wiki.answers.com/Q/What_are_the_differences_between_luminous_or_non_luminous_flames
Pang Seok Mun said
at 7:29 pm on Oct 5, 2011
Okay, Noted! Thank you too! :D
johnlittlephysics said
at 7:58 am on Oct 5, 2011
Hi Seok Mun, for questions on topics, post on pages for the topics for your class (T3). thank you.
Pang Seok Mun said
at 9:09 pm on Oct 4, 2011
What will happen to the packing of molecules if the melting point increases because the experiment is conducted at a lower altitude?
johnlittlephysics said
at 8:04 am on Oct 5, 2011
The change in melting point just changes the temperature at which a substances turns from solid into a liquid state. The packing of molecules would just be related to the state of the substance at any time/temperature.
Pang Seok Mun said
at 7:28 pm on Oct 5, 2011
Thank You Mr Ang! :D
Pang Seok Mun said
at 9:11 pm on Oct 4, 2011
When item A is said to be at a higher temperature then item B, this means that item A has more internal energy than item B? or Item A loses heat energy to item B when they are in contact?
johnlittlephysics said
at 8:10 am on Oct 5, 2011
1. higher temperature only means higher average kinetic energy of molecules in a substance.
If A and B are of different substances, their p.e. of molecules would be different since spacing would be different due to the nature of the substance, how the molecules are arranged. Other factors that also affect the internal energy include: mass of each item, state of each item,
2. If A and B are in contact, yes, A loses heat to B, as heat flows from region of higher temperature to a region of lower temperature. This heat transfer stops when A and B reach the same temperature.
Pang Seok Mun said
at 7:28 pm on Oct 5, 2011
Thank you! :D
Pang Seok Mun said
at 10:50 am on Oct 16, 2011
Mr Ang, Why isn't there 2008 EOY Science Paper Answer Key for Booklet A and D?
johnlittlephysics said
at 8:49 pm on Oct 16, 2011
If I remember correctly, the answer sheet to 2008 EOY Science Paper was issued to the class separately (on a later day), from the paper itself.
Goh Ying Ting said
at 12:10 pm on Oct 16, 2011
Mr Ang, if they ask us: when body X is said to be at a higher temperature than body Y, this means that...
a)body X has more internal energy than body Y
b)body X loses heat energy to body Y when they are in contact
the answer is b. why isn't it a?
thanks
johnlittlephysics said
at 8:51 pm on Oct 16, 2011
Temperature gives an indication of the average k.e. of molecules (but mass will also affect the total k.e. of molecules)
Internal energy = k.e. + p.e. of molecules, but there is no information to compare the p.e. of molecules.
You don't have permission to comment on this page.