chapter 10- heat

Question 1

explain the movement of a convection current.

Answer 1

1.talk about the heat/cold source
2.heat gain or loss
3. expansion or contraction
4. density drop or increase
5. direction of movement of particles(hot air rises/ cooler air sinks)
6. “a convection current is formed”

Question 2

why does the shiny surface emit more heat than the dark one?

Answer 2

the shiny surface is a poor emitter of radiant heat so the rate of heat loss by radiation is reduced .

Question 3

general convection notes:

Answer 3

-convection cannot be set up [hot remains at the top since less dense] so heat travels to ice by conduction.

-water is a poor conductor of thermal energy

Question 4

why does cork cause heat loss to be slower ?

Answer 4

it is a poor conductor of thermal energy. the rate of heat loss due to convection & conduction is reduced.

Question 5

why does a vacuum cause heat loss to be slower?

Answer 5

heat loss due to convection & conduction is reduced as these processes require a medium to take place

Question 6

why does silvered glass walls reduce the rate of heat loss?

Answer 6

reduces heat loss that is due to radiation as silver is a poor emitter of radiant heat

Question 7

bimetallic strip notes:

Answer 7

as the room cools down, brass contracts faster than iron in the bimetallic strip will cause the strip to bend away from the contact. this creates an open circuit which will then cut off the current flowing through the circuit.