19.2 Flashcards
What is meant by heating up?
The process of increasing the temperature of an object by supplying energy.
What is meant by cooling down?
The process of decreasing the temperature of an object by removing energy.
Which materials heat up and cool down the fastest?
Materials with lower specific heat capacities heat up and cool down the fastest.
Define specific heat capacity.
The energy needed to raise the temperature of unit mass of a substance by 1K without change of state.
What is the unit of specific heat capacity?
J kg^-1 K^-1.
What factors influence the temperature rise of an object when heated?
- Mass of the object
- Amount of energy supplied
- Substance or substances of the object
What is the equation for calculating energy needed to raise the temperature of a substance?
Q = mc(T2 - T1).
What does the inversion tube experiment demonstrate?
The conversion of gravitational potential energy into internal energy when an object falls and hits the bottom of the tube
the temperatue is intially taken after the a particlular number of inversions
What is the equation for gravitational potential energy loss during the inversion tube experiment?
Loss of gravitational potential energy = mgLn.
What is the equation for the gain of internal enrgy of the led shot
mc delta t
In the inversion tube experiment, what happens each time the tube is inverted?
The temperature of the lead shot is measured after a number of inversions.
how do you work out specific heat capacity of lead in experiment
c = gln/delta t
What is used to measure the specific heat capacity of a metal electrically?
A block of the metal of known mass in an insulated container
A 12v electrical heater is inserted into a drilled hole in the metal supplying electrical energy
thermometer is entered into a second hole to measure temperature rise
What formula represents the electrical energy supplied to the heater?
Electrical energy = heater current I x heater pd V x heating time t
therefore what is IVt equal to
mcΔT
How is specific heat capacity (C) calculated? using electrical method
C = IVt / mΔT
What improves the thermal contact between the thermometer and the metal?
A small amount of water or oil in the thermometer hole
What is the formula to calculate the electrical energy supplied to a heater?
Electrical energy = heater current I x heater pd V x heating time t
how do you measure specific heat capacity of a liquid
add a known mass of liquid into a calorimeter of down mass and known specific heat capacity
a 12 v electrical heater is placed within the liquid and heat it directly
a thermometer is inserted into the liquid to measure temp rise
What is the equation for the energy needed to heat a liquid?
Energy needed = mass of liquid (m) × specific heat capacity (c) × temperature rise (ΔT)
what Is electrical energy supplied equal to
itv
What is the formula to calculate the energy needed to heat the calorimeter?
Energy = mass of calorimeter (mcal) x specific heat capacity of calorimeter (cal) x temperature rise (ΔT)
This formula assumes no heat loss to the surroundings.
what is ivt of liquid experiment equal to
mc delta t +mcal Ccal delat t
example of continuous flow heating
electrical shower
water passes through copper coils heated by an electrical heater.
the water is hotter at the outlet than inlet
the electrical energy supplied per second by continuous flow heating =
iv = mc delta T/t
same for liquid in solar panel heating
