help brothers homework

[glider14]

ok my brother is in 6th grade and he forgot his science book...again! his homework is on "the nature of heat" and wether each of these is: conduction, radiation, or convection.
im a geunies when it comes to science but this just befuddles me. could you guys help?

1. an entire lake is heated by water from a hot spring at the bottom of a lake.

2.sunlight melts a wax crayon left outside.

3. a burner on a stove heats the bottom of a pot.

4 the inside frame of your front door feels cold during the winter.

5. a kite rises high above a hot sandy beach.

6. you feel the warm glow of a bonfire.
thanks again
alex

 

[glider14]

k fixed

 

[Gawd_oOo]

1. an entire lake is heated by water from a hot spring at the bottom of a lake.
convection

2.sunlight melts a wax crayon left outside.
radiation

3. a burner on a stove heats the bottom of a pot.
depends on if it is a gas or electric stove. Gas - Radiation & Convection. Electric - Radiation & Conduction & Convection

4 the inside frame of your front door feels cold during the winter.
Conduction

5. a kite rises high above a hot sandy beach.
Convection

6. you feel the warm glow of a bonfire.
Radiation

 

[glider14]

thanks gawd. he had all them right except for #5

 

[Gawd_oOo]

5 The radiant heat from the sun warms the sand, the sand warms the air just above it by radiation, then the warm air rises (convection) which is what makes the kite fly.

 

[herenorthere]

#1 is a bad example because that spring is adding hot water, not just heat, meaning there's mass transfer going on in addition to energy transfer. Good thing he's in 6th grade, not in a 3rd year chemical engineering class, or the equations could get brutal.