Name:________________________________ Date: _______________ Period:________
Thermal Energy Concepts
Complete the following table
Concept
Description/Definition
Symbol
Unit
Temperature
A measure of the average kinetic energy of the particles in an
object.
˚C, ˚F, K
Thermal Energy
The sum of the kinetic AND potential energy of the particles in
an object.
Joules
Heat
Thermal energy that FLOWS from something at a HIGHER
temperature to something at a LOWER temperature.
Joules
Specific Heat
The amount of thermal energy needed to raise 1 kg of a
substance by 1˚C (or Kelvin).
Q = c m T
(T = Tfinal - Tinitial )
In the formula above what does the symbol m represent?
Mass
In the formula above what does the symbol T represent?
Change in Temperature
How do you calculate T?
Final Temperature – Initial Temperature
(T = Tfinal - Tinitial )
J/kg˚C
Complete the following practice problems.
1. Find the change in thermal energy of a 20-kg wooden chair that warms from 15ºC to 30ºC if the
specific heat of the wood is 700 J/(kgºC).
Formula: Q = cmT
210,000J = 20 kg x 700 J/(kgºC) x 15ºC
2. Find the change in thermal energy of a 20-kg wooden chair that cools from 55ºC to 20ºC if the
specific heat of the wood is 700 J/(kgºC).
Formula: Q = cmT
-490000J = 20 kg x 700 J/(kgºC) x -35ºC
3. How much energy is needed to heat 1 kg of sand from 30ºC to 50ºC; sand has a specific heat of 664
J/(kgºC).
Formula: Q = cmT
13280J = 1 kg x 664 J/(kgºC) x 20ºC
4. If a 30-g silver coin cools from 40ºC to 20ºC, what is the change in its thermal energy? The specific
heat of silver is 235 J/(kgºC).
Formula: Q = cmT
-141J = 0.03 kg x 235 J/(kgºC) x -20ºC
5. The air in the classroom has a mass of 100 kg and a specific heat of 1,020 J/(KgºC). What is the
change in thermal energy of the air when it warms from 18ºC to 22ºC?
Formula: Q = cmT
408000J = 100 kg x 1020 J/(kgºC) x 4ºC
6. What is the change in thermal energy of a 50 Kg block of iron if its temperature changes from 60ºC
to 80ºC? The specific heat of iron is 450 J/(KgºC).
Formula: Q = cmT
450000J = 50 kg x 450 J/(kgºC) x 20ºC
Challenge Questions (Need to rearrange the equation to solve)
1. A sample of an unknown metal has a mass of 0.5 kg. Adding 1,985 J of heat to the metal raises its
temperature by 10ºC. What is the specific heat of the metal?
Formula: c = Q/mT
1985J/ (0.5kg x 10ºC) = 397 J/(kgºC)
2. The temperature of a block of iron, which has a specific heat of 405 J/(kgºC), increases by 3ºC when
2700 J of energy are added to it. What is the mass of this block of iron?
Formula: m = Q/cT
2700J/ (405 J/(kgºC) x 3ºC) = 2.2 J/(kgºC)