Heat and Materials

Question 1

What is a conductor?

Answer 1

A material that allows heat to pass through it easily.

Question 2

Why does a metal spoon feel hotter than a wooden spoon when placed in hot water?

Answer 2

Because metal is a better conductor of heat than wood.

Question 3

What is an insulator?

Answer 3

A material that does not conduct heat well, like wood or plastic.

Question 4

Why do we use glass or metal dishes in an oven instead of plastic?

Answer 4

Plastic melts easily, but glass and metal can withstand high temperatures.

Question 5

Which has a higher specific heat: water or sand?

Answer 5

Water has a higher specific heat than sand.

Question 6

True or False: Sand heats up faster than water because it has a lower specific heat.

Answer 6

True

Question 7

True or False: Insulators help transfer heat quickly.

Answer 7

False (Insulators slow the transfer of heat.)

Question 8

True or False: Thermal expansion causes materials to contract as they heat up.

Answer 8

False (Materials expand when heated.)

Question 9

True or False: Metal is a good conductor because it allows heat to transfer easily.

Answer 9

True

Question 10

True or False: Wool and air are examples of insulators.

Answer 10

True or False: Wool and air are examples of insulators.

Question 11

Why does water take longer to heat up than sand?

Answer 11

It has a higher specific heat capacity

Question 12

What happens to the particles in a material as it cools down?

Answer 12

They move closer together

Question 13

Which material would be the best insulator?

Answer 13

Wool

Question 14

What causes popcorn to pop?

Answer 14

Heat from the microwave expanding water vapor inside the kernel

Question 15

How does thermal expansion help you open a stuck jar lid?

Answer 15

When you run hot water over the lid, it expands more than the glass jar, loosening the lid.

Question 16

What is the formula to calculate energy change when a material’s temperature changes?

Answer 16

Energy Change = Mass × Specific Heat × Temperature Change

Question 17

Describe why metal feels cold to touch even at room temperature.

Answer 17

Metal is a good conductor and transfers heat away from your hand quickly, making it feel cold.

Question 18

Explain how popcorn pops using thermal expansion and kinetic energy.

Answer 18

Heat causes the water inside the popcorn kernel to turn to vapor. As the vapor expands, it builds pressure until the kernel pops. This expansion is related to the increase in kinetic energy as the temperature rises.

Question 19

If you heat 2 kg of water and its temperature rises by 5°C, and the specific heat of water is 4,186 J/kg*K, how much energy was used to heat the water?

Answer 19

41,860 J

Question 20

Why do cracks often appear in concrete sidewalks or roads during very hot weather, and how is this related to thermal expansion?

Answer 20

Cracks appear in concrete sidewalks or roads during very hot weather because concrete expands as it heats up. When the temperature rises, the particles in the concrete spread out and cause the material to expand. If there isn’t enough space for this expansion, the concrete can crack. This is a result of thermal expansion, which happens when materials increase in volume as their temperature increases.