# Lesson Notes By Weeks and Term - Junior Secondary School 2

THERMAL ENERGY I

TERM: 2nd TERM

SUBJECT: BASIC SCIENCE

CLASS:  JSS 2

REFRENCE

• Precious seed BASIC SCIENCE FOR JUNIOR SECONDARY SCHOOLS BOOK 2

WEEK NINE                                                                                     DATE: ………………..

TOPIC: THERMAL ENERGY I

Heat flow is the movement of heat (energy) from the interior of Earth to the surface.  The source of most heat comes from the cooling of the Earth’s core and the radioactive heat generation in the upper 20 to 40 km of the Earth’s crust.

Energy flows into your body from the surrounding air, from surrounding objects, and from the sun when you're outside, or even light bulbs when you're inside. Energy also flows out of your body into the surrounding air, into the surrounding objects, and even into outer space, most notably if you are outside on a clear night. Heat flow moves energy from a higher temperature to a lower temperature.    The bigger the difference in temperature between two objects, the faster heat flows between them.   When temperatures are the same, there is no change in energy due to heat flow. Heat has the units of energy; heat flow has the units of power.

This type of energy transfer from one place to another place is driven by differences in temperature and is called heat flow

Way Heat Flows

1. There has to be a temperature difference. Energy only flows as heat if there is a temperature difference.
2. Energy as heat flows from a higher temperature to a lower temperature.
3. The greater or larger the difference in temperature, the faster the energy flows.

EVALUATION

1. What do you understand by heat flow?
2. Mention the three things to know about heat flow

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HEAT FLOWS

• Heat flow from the sun to the plants and algae and some types of bacteria is the energizer of photosynthesis
• A steam boiler converting the chemical energy stored in coal (in the old days) or fuel oil or natural gas (more common nowadays), into "heat" which was used to convert liquid water into gas phase water (steam to you laymen). The steam flowed up into the radiators where its heat was transferred by conduction to the air and by radiation to the objects in the room.
• Because of heat flow, cold-blooded reptiles and insects that live in cold climates only come out in the summer. Heat flow is why there are a lot more reptiles and insects in equatorial climates than arctic climates.
• Warm-blooded mammals and birds with their high metabolisms and hotter bodies can live and move in some pretty cold places. But, because of heat flow, they have to have good dry fur or feathers, or a good layer of blubber, and plenty of high energy food to keep that body heat coming.
• When you put on a jacket in the winter, or wear shorts on a hot day, you are adjusting your heat flow, trying to help your body keep its temperature very close to 38 degrees C (98.6 deg. F). It's a never ending struggle. Energy as heat is always flowing out of, and into, your body.
• Car radiators are used to transfer heat out of the car engine.
• Elephant ears act like giant radiators to transfer heat out of their bodies.

Precious seed BASIC SCIENCE FOR JUNIOR SECONDARY SCHOOLS BOOK 2 pages 139

EVALUATION

1. What do you understand by heat flow?
2. Mention the three things to know about heat flow
3. What are the Three Things To Know about the way heat flows?
4. Define heat flow.

WEEKEND ASSIGNMENT

1. ----------is the movement of heat (energy) from the interior of Earth to the surface.  A. Heat flow B. Energy flow C. Power flow D. Temperature fling
2. Heat flow moves ----------from a higher temperature to a lower temperature. A. energy B. power C. work D. gravity
3. Heat has the units of energy; heat flow has the units of-------- A.  power B. energy C. force D. work
4. Heat flow from the sun to the plants and algae and some types of bacteria is the ---------of photosynthesis. A. energizer B. gravitational C. appetizer D. none
5. ----------- mammals and birds with their high metabolisms and hotter bodies can live and move in some pretty cold places. A. Warm-blooded B. Cold-blooded C. Chilled-blooded D. All of the above

THEORY

1. Define heat flow.
2.  What are the three things to know about the way heat flows?