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๐ฌ One capacity, many costumes
The energy in your food, in a glowing bulb, in a ringing bell — same idea, different forms. And one form can turn into another.
What are the different forms of energy?
Forms of Energy
Mechanical — motion or position Thermal — warmth or heat Light — lets us see Sound — vibrations of air Electrical — moving charges Nuclear — stored in nuclei Chemical — in fuels and food One form can change into another.
- Energy exists in many forms: mechanical (motion or position), thermal (warm/hot), light , sound , electrical , nuclear (stored in nuclei), and chemical (stored in fuels and food).
- Energy can change from one form to another: electrical → light in a bulb; chemical (food) → mechanical in our muscles; mechanical → sound in a ringing bell.
- We will focus next on mechanical energy , since it connects directly to the forces and motion studied earlier.
Important Definitions
- Forms of energy — energy can exist as mechanical, thermal, light, sound, electrical, nuclear and chemical energy, and can be converted from one form to another.
- Chemical energy — energy stored in fuels and food in the form of chemical bonds between atoms.
โธโถ Pause and Ponder
- 3. Pedalling a bicycle on a flat road: the chemical energy in your muscles becomes mainly mechanical (kinetic) energy of the moving bicycle, along with some thermal energy (your body and the moving parts warm up) and a little sound energy .
NCERT Question 4 — For each of the following
For each of the following situations, identify the energy transformation that takes place: (i) a truck moving uphill, (ii) unwinding of a watch spring, (iii) photosynthesis in green leaves, (iv) water flowing from a dam, (v) burning of a matchstick, (vi) explosion of a fire cracker, (vii) speaking into a microphone, (viii) a glowing electric bulb, and (ix) a solar panel.
โ Test Yourself
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Name any four forms of energy.
Show Answer
Mechanical, thermal, light, sound, electrical, nuclear and chemical energy (any four). -
What energy change happens in a glowing electric bulb?
Show Answer
Electrical energy is converted into light energy and thermal energy. -
What energy change happens in the food we eat?
Show Answer
The chemical energy stored in the food is converted into mechanical energy by our muscles. -
Which form of energy will we study most closely in this chapter, and why?
Show Answer
Mechanical energy — because it is directly connected to the forces and motion we studied earlier.
