Specific heat capacity

Question 1

WHat does the temperature rise of an object depend on?

Answer 1

• mass of the object
• amount of energy supplied to it
• substance(s) the object is made from

Question 2

WHat is specific heat capacity and what are its units?

Answer 2

• specific heat capacity, c, of a susbtance is the energy needed to raise the temperature of a unit mass of the substance by 1 K without a change in state
• J kg^-1 K^-1

Question 3

How does the inversion tube experiment determine specific heat capacity?

Answer 3

• GPE converted to IE
• therfore for n number inversion, loss of GPE = mgL
• gain of IE = mcΔT
• therfore mcΔT = mgLn
• so C = gLn / ΔT

Question 4

How can specific heat capacity of a metal be measurted?

Answer 4

• 12V heater inserted into a hole
• supplies measured amount of electrical energy
• place thermoment to measures temperature rise
• electrical energy suppliied = IVt
• assume no lost to surrounding mcΔt = IVt
• therefore c=IVt / mΔT

Question 5

How do you measure the specific heat capacity of a liquidf?

Answer 5

• known mass of liquid in an insulated caloprimeter of known mass and specific heat capacity
• 12V heater placed in the liquidf
• thermometer used to measure temperature rise
• electrical energy supplied = IVt
• energy needed to meat liquid = m_L x c_L x ΔT
• energy needed to heat calorimeter = m_c x c_c x ΔT
• IVt = m_Lc_LΔT + m_cc_cΔT

Question 6

In continuous flow heating, how can electrical energy supplied per second (power) be measuerd?

Answer 6

• e.g. in shower, water hotter at outlet then inlet
• for mass m of liquid, passing through heater in time t at steady flow, assuming now heat loss
• IV = mcΔT / t