Physics' Concept - 3

Classical Mechanics Level 1

Potential energy of an object with mass 'm' placed at a height of 'h' from the ground = mgh . This means as the height of an object from ground increases , its potential energy also increases. Using this as a fact , what can you say about the statement below :

" Since the potential energy increases with height and potential energy is stored energy, a piece of coal when placed at a very high altitude from sea level releases more (stored) energy when burnt as compared to when it is placed on ground(sea level)"

Sometimes true True There is difference in energy release , but it is too small. False

Nihar Mahajan by Nihar Mahajan , 20, India

This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try refreshing the page, (b) enabling javascript if it is disabled on your browser and, finally, (c) loading the non-javascript version of this page . We're sorry about the hassle.

5 solutions

Nihar Mahajan
May 18, 2015

There is an increase in the potential energy , but this energy increase refers to the energy between the molecules of coal piece and it has no relation with energy released by burning it. Thus , the statement is false and the coal piece releases the same energy when burnt at any place under same temperature and pressure condition.

14 Helpful 0 Interesting 0 Brilliant 0 Confused

Good solution..Already upvoted... Nihar Mahajan

Rahul Singh - 6 years ago

Log in to reply

Thanks!!!!!

Nihar Mahajan - 6 years ago

also the potential energy is based on reference........so we can even consider the coal at the ground to have more PE

Kislay Raj - 6 years ago

Log in to reply

Potential energy is reference dependent but change in potential energy is independent of reference..!!

Rohit Gupta - 6 years ago

Good one! @Nihar Mahajan

Sravanth C. - 6 years ago

Log in to reply

Cheers! xD

Nihar Mahajan - 6 years ago

Lol I was thinking that since there is less air the higher you go, the fire wouldnt burn xD

CS ಠ_ಠ Lee - 6 years ago
Ramesh Goenka
May 18, 2015

In case of coal, the energy being released when burnt is due to the chemical energy , worked upon by heat and pressure , buried beneath the rust. The stored potential energy can be converted into kinetic energy but cannot be converted into the chemical energy.

2 Helpful 0 Interesting 0 Brilliant 0 Confused
Hon Ming Rou
Jun 21, 2015

Potential energy is related to the law of motion, nothing related to heat energy.

0 Helpful 0 Interesting 0 Brilliant 0 Confused
Rohit Gupta
Jun 6, 2015

Gravitational potential energy is the energy between the earth and the coal system and it is stored inside the field around it. When we raise a coal piece then the field in the surrounding change and hence the potential energy changes.

When we burn the coal then equal amount of heat energy is produced but then when the ashes left from the coal come down it will release its gravitational potential energy and as the ashes come down it heats the atmosphere and eventually release more energy :P

0 Helpful 0 Interesting 0 Brilliant 0 Confused
Harshit Agarwal
May 27, 2015

There is an increase in the potential energy , but this energy increase refers to the energy between the molecules of coal piece and it has no relation with energy released by burning it. Thus , the statement is false and the coal piece releases the same energy when burnt at any place under same temperature and pressure condition.

0 Helpful 0 Interesting 0 Brilliant 0 Confused

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...