Lesson Notes By Weeks and Term v4 - SHS 3

Lesson Video

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Performance objectives

• Define heat and its significance.
• Describe the three modes of heat transfer.
• Apply the concept of specific heat capacity to calculate heat transfer.
• Analyze real-life scenarios involving heat.

Lesson summary

This lesson explores the fundamental concepts of heat energy, a topic we experience every day in Ghana. From the heat of the sun that dries our cocoa beans to the energy we use to cook our favourite meals like *banku* or *jollof* rice, understanding how heat is measured and transferred is crucial. We will investigate why some materials, like water, take a very long time to heat up, while others, like a metal spoon, get hot almost instantly. We will also learn about the large amount of energy required to change a substance from solid to liquid (like melting ice) or from liquid to gas (like boiling water to make steam), even when the temperature isn't changing.

Lesson notes

2.1. Heat vs. Temperature

Many people use "heat" and "temperature" to mean the same thing, but in Physics, they are very different. Temperature: This is a measure of the degree of hotness or coldness of a body. It tells us the average kinetic energy of the particles (atoms or molecules) in a substance. A higher temperature means the particles are moving or vibrating faster. Unit: Kelvin (K) is the SI unit. We also commonly use degrees Celsius (°C). Analogy: Temperature is like the *speed* of a car. Heat: This is the form of energy that is transferred from a hotter body to a colder body due to the temperature difference between them. It is energy in transit. Unit: Joules (J), since it is a form of energy. Analogy: Heat is like the *distance* the car travels.

Think about it this way: A large bowl of warm water at 40°C has a lower temperature than a small cup of boiling water at 100°C. However, the large bowl of water contains much more total heat energy because it has far more particles. 2.2. Specific Heat Capacity (c)

Have you noticed that on a hot day at Labadi beach, the sand gets extremely hot, but the sea water stays relatively cool? This is because of their different specific heat capacities. Definition: The specific heat capacity of a substance is the quantity of heat energy required to raise the temperature of a unit mass (1 kg) of that substance by one degree Kelvin (1 K) or one degree Celsius (1 °C). Formula: `Q = mcΔθ`

Evaluation guide

• Use momentum change to establish impulse and hence deduce Newton's second
• law of motion.
• Enquiry learning :
•  Let learners use the principle of conservation of momentum to establish an equation to