ENERGY & HEAT

Question 1

energy

Answer 1

• It is the ability to do work
• Energy can take several forms and it is transferred from one object to another one in order to perform on it .
• We measure energy in Joules ( symbol : J)

Question 2

conversation law of energy

Answer 2

Energy cannot be destroyed or created .It is only transferred from one object to another one

Question 3

heat

Answer 3

• Thermal energy
• comes from a substance whose molecules are vibrating faster.
• transferred from colder objects to hotter ones.
• We measure heat in joules (symbol: J) as it is a form of energy.

Question 4

conduction

Answer 4

occurs when two objects of different temperature are placed in direct contact with each other. Heat energy moves out of the warmer object and into the cooler object until both objects are at the same temperature.

Question 5

convection

Answer 5

occurs when a fluid (liquid or gas)physically moves into an area of different temperature and then heats this area up, or cools it down, as a result.

Question 6

radiation

Answer 6

when heat energy is gained or lost by way of electromagnetic radiation.
The best example of this is the sun, shown below. The electromagnetic radiation from the hot sun reaches the cooler earth and heats it up as a result. When the sun goes behind a cloud this radiation is mostly blocked and the sun is not able to heat the earth as much.

Question 7

conductors

Answer 7

materials that allow heat to pass through them.

Question 8

insulators

Answer 8

materials that DO NOT ALLOW heat to pass through them.

Question 9

5 forms of energy

Answer 9

• Mechanical energy is all about motion : jumping frog , moving auto
• Thermal energy is all about heat : melting ice cream , heating a soup
• Electromagnetic energy is all about light waves : visible light (colors) , radio waves , X-rays etc
• Electrical energy is all about electricity : power lines , lighting
• Chemical energy is all about a chemical reaction , burning something : food ,light on a match