Question

directions: choose the best energy transfer option for the pictures below.
an oven mitt gets warmer while
marshmallow heats over a fire
the sun causes water in a pond
transporting a hot baking dish
to evaporate
conduction
hot air inflates a hot air
heat from the table is
a hot horseshoe transfers heat
balloon
absorbed by ice cubes.
to the tongs
a pot sitting on a hot burner
a bowl of oatmeal cools
water is warmed over a fire
a spoon gets warmer after
a microwave heats food using
an infrared heat sensor
sitting in a bowl of soup
microwaves via the
detects body heat
electromagnetic spectrum

Explanation:

• Marshmallow heats over a fire: Heat is transferred through radiation. Fire emits infrared radiation which heats the marshmallow.
• The sun causes water in a pond to evaporate: The sun emits electromagnetic radiation (including infrared). This radiation transfers energy to the water molecules, causing them to evaporate. So, it is radiation.
• Hot air inflates a hot air balloon: Hot air (less dense) rises and inflates the balloon. This is convection as it involves the movement of a fluid (air) due to temperature differences.
• Heat from the table is absorbed by ice cubes: The table (solid) transfers heat to the ice (solid - initially). This is conduction as heat is transferred through direct contact in solids.
• A hot horseshoe transfers heat to the tongs: The horseshoe (solid) and tongs (solid) are in contact. Heat transfer is by conduction.
• A pot sitting on a hot burner: The burner (solid) and pot (solid) are in contact. Heat transfer is by conduction.
• A bowl of oatmeal cools: The oatmeal (hot) loses heat to the surrounding air. The air near the oatmeal gets heated, rises (convection currents), and cooler air comes in contact with the oatmeal. So, it is convection.
• Water is warmed over a fire: The fire emits radiation. The water (in the container) absorbs this radiation. So, it is radiation.
• A spoon gets warmer after sitting in a bowl of soup: The spoon (solid) and soup (liquid - but here, since the spoon is in direct contact, and assuming the soup is in a relatively still state in terms of large - scale movement for the spoon's heating, conduction is the main mode as heat is transferred through direct contact).
• A microwave heats food using microwaves via the Electromagnetic Spectrum: Microwaves are a form of electromagnetic radiation. The food absorbs these microwaves (radiation) and gets heated.
• An infrared heat sensor detects body heat: The body emits infrared radiation. The sensor detects this radiation. So, it is radiation.

Answer:

1. Marshmallow heats over a fire - Radiation
2. The sun causes water in a pond to evaporate - Radiation
3. Hot air inflates a hot air balloon - Convection
4. Heat from the table is absorbed by ice cubes - Conduction
5. A hot horseshoe transfers heat to the tongs - Conduction
6. A pot sitting on a hot burner - Conduction
7. A bowl of oatmeal cools - Convection
8. Water is warmed over a fire - Radiation
9. A spoon gets warmer after sitting in a bowl of soup - Conduction
10. A microwave heats food using microwaves via the Electromagnetic Spectrum - Radiation
11. An infrared heat sensor detects body heat - Radiation