Hi Mr. Doner, thank you so much for your videos - they are very useful. Just a note, on 12:44 it says "head capacity" instead of "heat capacity". Keep up the amazing work and thank you!
at 20:35, part (i). I understand how you used the same specific heat capacity and time (since the rate at which heat is being added is the same); but I did not get why you used the ice's mass (0.25kg), while using the specific heat capacity of water, shouldn't they be consistant?
Hi Mr. Doner, I have a question regarding the table you have shown in 12:42. In this video you have given me the table but in the exam will we be given this table which shows the heat capacity of different molecules?? I checked in the IB Physics databooklet and there is no such table given there :( Should I memorize the numbers for every substance or will I get it along with the question???? Pls give me an answer soon!!! I have to prepare for an exam this Thursday :(((( Thank u! P.S. You teach very well :)
@@donerphysics Ahh ok! but in the examples that you gave, were the numbers automatically part of the question? At 12:40 are those IB questions?? Thankyou for your reply!!
Hi Mr. Doner. the question you solved at 17:34 asked for an answer in Joules, not calories. in an IB exam, Could I be deducted marks for answering with the wrong unit? if you do 25 (25J/g)*500g, the result is 12500J, but if you do it the way you did, you arrive at 2950 calories (*4.184) is 12342.8 J. wouldn't working from joules be more precise for this question? I appreciate your work a lot, your videos have helped me a lot in IB physics HL so far, thank you so much!
IB will work in SI units. They will not use calories. I find them helpful just because it is easier to remember the specific and latent heats of water.
Hi, I noticed that at 20:10, the specific heat capacity of water is paired with kelvin, but the temperate that was use in the calculation is in Celsius. Does this mean we don't need to work out the conversion?
Though temperatures are very different in kelvin compared to celcius, temperature differences are the same. An increase of 1K is the same as an increase by 1C.
Thank you so much for your videos, I recently changed school and I need to catch up on some topics I haven't studied before and your explanations are sooo good!!
It really all depends all on the units for c. If c is J/kg.K then energy would be in joules, mass in kg, and temperature in Kelvin (Temp. would also work in celcius since the change in temp. is the same in both units.)
Hi, Mr Doner, I do not understand what how you solved part (i) of the question at 18:00. I don't understand why you used the specific heat capacity of water and not ice and then you ended up finding the power which was already given in the question.?
We had enough information for the water (namely we have its specific heat but we don't know the latent heat of the ice) to find out to find out how much power was being added to the water. The power is supplied by a heater at the same rate for all 3 phases. We are asked to verify (deduce) that the power was 530 W, so we can not use this as a given in the problem.
Either column will work. You just need to be consistent. IB will not use calories but it is just a unit of energy that typically gives nicer numbers than Joules (so nicer numbers is my reason). Make sure you express mass in kg if you use the second column.
Hi Mr Doner, What is the difference between kilo calories and calories? You seemed to use them interchangeably. Also, do we have to know how to convert between joules and calories? Lastly, my teacher used joules mostly, not calories, which one does IB use and prefer? Thanks!
a kilocalorie is 1000 calories. When we count calories for eating, we are really using kilocalories but we call them calories. IB will use Joules not calories. I often use calories because it simplifies calculations.
Thanks for the super useful video. Should the definition of specific heat not be "the energy required to raise the temperature of 1kg of substance by 1K" since its per unit mass?
I'm a little confusd by the definition of a 'calorie'; is it just the (c) specific heat capacity of the substance? If so, why did Mr. Doner use calories when talking about phase changes e.g. 5.9 cal/g to melt lead?
A calorie is defined as the amount of energy required to raise the temperature of 1 gram of water by on degree. If you have ice at its melting point, it requires 80 calories to melt one gram. A calorie is an amount of energy like Joules.
Hi Mr. Doner, thank you so much for your videos - they are very useful.
Just a note, on 12:44 it says "head capacity" instead of "heat capacity".
Keep up the amazing work and thank you!
Thanks I will add an annotation.
at 20:35, part (i). I understand how you used the same specific heat capacity and time (since the rate at which heat is being added is the same); but I did not get why you used the ice's mass (0.25kg), while using the specific heat capacity of water, shouldn't they be consistant?
Hi Mr. Doner, I have a question regarding the table you have shown in 12:42. In this video you have given me the table but in the exam will we be given this table which shows the heat capacity of different molecules?? I checked in the IB Physics databooklet and there is no such table given there :( Should I memorize the numbers for every substance or will I get it along with the question???? Pls give me an answer soon!!! I have to prepare for an exam this Thursday :(((( Thank u!
P.S. You teach very well :)
There is never any need to memorize a number with the IB. All numbers are either given in the data booklet or given in the individual question.
@@donerphysics Ahh ok! but in the examples that you gave, were the numbers automatically part of the question? At 12:40 are those IB questions??
Thankyou for your reply!!
Hi Mr. Doner. the question you solved at 17:34 asked for an answer in Joules, not calories. in an IB exam, Could I be deducted marks for answering with the wrong unit?
if you do 25 (25J/g)*500g, the result is 12500J, but if you do it the way you did, you arrive at 2950 calories (*4.184) is 12342.8 J. wouldn't working from joules be more precise for this question?
I appreciate your work a lot, your videos have helped me a lot in IB physics HL so far, thank you so much!
IB will work in SI units. They will not use calories. I find them helpful just because it is easier to remember the specific and latent heats of water.
Hi, I noticed that at 20:10, the specific heat capacity of water is paired with kelvin, but the temperate that was use in the calculation is in Celsius. Does this mean we don't need to work out the conversion?
Though temperatures are very different in kelvin compared to celcius, temperature differences are the same. An increase of 1K is the same as an increase by 1C.
Great video Mr. Doner!
Thank you so much for your videos, I recently changed school and I need to catch up on some topics I haven't studied before and your explanations are sooo good!!
You are so welcome!
For these formulas does Q have to be in J or cal, m in grams and temperature in celsius?
It really all depends all on the units for c. If c is J/kg.K then energy would be in joules, mass in kg, and temperature in Kelvin (Temp. would also work in celcius since the change in temp. is the same in both units.)
Hi, Mr Doner, I do not understand what how you solved part (i) of the question at 18:00. I don't understand why you used the specific heat capacity of water and not ice and then you ended up finding the power which was already given in the question.?
We had enough information for the water (namely we have its specific heat but we don't know the latent heat of the ice) to find out to find out how much power was being added to the water. The power is supplied by a heater at the same rate for all 3 phases. We are asked to verify (deduce) that the power was 530 W, so we can not use this as a given in the problem.
Hi Mr. Doner, could you please tell me why you chose the value for c from the first column and not the second column at 14:00
Either column will work. You just need to be consistent. IB will not use calories but it is just a unit of energy that typically gives nicer numbers than Joules (so nicer numbers is my reason). Make sure you express mass in kg if you use the second column.
Chris Doner thank you sir
Hi Mr Doner,
What is the difference between kilo calories and calories? You seemed to use them interchangeably. Also, do we have to know how to convert between joules and calories? Lastly, my teacher used joules mostly, not calories, which one does IB use and prefer?
Thanks!
a kilocalorie is 1000 calories. When we count calories for eating, we are really using kilocalories but we call them calories. IB will use Joules not calories. I often use calories because it simplifies calculations.
does the first graph have to start with -50 or can it be any number
any number
You make the best videos on thermal energy.
Do we need to memorize the latent heat values for water and other substances?
You don't need to remember any numbers in IB physics.
I love you Mr. Doner
Hey mr.doner, why does the given heat capacity only work for one part of the curve?
The specific heat capacity for the solid is not the same as for the liquid or gas. Water has about 2X the specific heat capacity of ice.
Thanks for the super useful video. Should the definition of specific heat not be "the energy required to raise the temperature of 1kg of substance by 1K" since its per unit mass?
1K is the same as 1oC. They are an equal rise in temperature.
this video is greatttt
in the first example u used joules and the second example u used calories for hammer question. any specific reason? thank u
To help you be familiar with both units. IB will use Joules or Kilojoules.
Thanks so much for all your videos! Could I ask which paper the question min 18 onwards was from? Please keep doing what you are doing :-)
My pleasure but sorry I do not remember which exam the question was from.
I will give a like to all of your videos
I'm a little confusd by the definition of a 'calorie'; is it just the (c) specific heat capacity of the substance? If so, why did Mr. Doner use calories when talking about phase changes e.g. 5.9 cal/g to melt lead?
A calorie is defined as the amount of energy required to raise the temperature of 1 gram of water by on degree. If you have ice at its melting point, it requires 80 calories to melt one gram. A calorie is an amount of energy like Joules.
what do you mean by threshold?
A threshold is a set off point. For instance, we might say if the thermostat is set for 70 degrees, the threshold for the furnace to turn on is 70.
Thanks a lot Sir
The second question at 7:14 is asking for "how much energy" not "how many calories" so wouldn't the answer be 418J ×1 ×2= 836J
Calories like Joules are units of energy.