Name : ____________________

CG : _______________

Name : ____________________

CG : _______________

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2014 JC1 H2 Physics Bridging Course

Part 4: Specific heat capacity and Specific latent heat (Thermal Physics)

Learning Outcomes:

You’ll be able to

(i) Define the terms heat capacity and specific heat capacity

(ii) Recall and apply the relationship thermal energy = mass specific heat capacity temperature change

(iii) Define the terms latent heat and specific latent heat

(iv) Apply the relationship thermal energy = mass specific latent heat to solve problems

(v) Sketch and interpret a cooling curve

A. Heat Capacity

Suppose we have two beakers of water, one containing 100 g and the other containing 1000 g. If we heat both beakers from 30 C to 60 C using the same heater, we will find that the 1000 g of water takes about ten times longer than 100 g of water to heat up. This means that 1000 g of water needs ten times the thermal energy required by 100 g of water to raise it to the same temperature. Therefore, 1000 g of water has ten times the heat capacity of 100 g of water.

Heat capacity is the amount of thermal energy required to raise the temperature of a body by 1 K (or 1 C). |

The above experiment also shows that the amount of thermal energy needed to raise the temperature of an object depends on the mass of the object.

The symbol for heat capacity is C. The units for heat capacity are J K-1 or J C-1.

We can express heat capacity C as

where Q = thermal energy absorbed in J,

= change in temperature in K or C.

Exercise 1

In a simple experiment, 100 g of water requires 12 600 J of thermal energy to raise it from 30C to

60 C.

(a) Find the heat capacity of 100 g of water.

Given: Heat supplied, Q = 12 600 J

Temperature raised, = 60 C – 30 C = 30 C.

Heat capacity for 100 g of water

C = Q/ = 420 J K-1...