Heating and cooling Flashcards
How does a convection current work?
A gas or a liquid is heated up and it rises. When it cools again enough it sinks again creating a circle.
Which insulates better a Mug, A black can or a Thermos flask
Thermos flask
What three things does the amount of energy needed to heat something depend on?
How much is being heated
What it is made of
The final temperature
Which of the following answers could refer to a hot day in the UK (Including Wales)?
30C 20C 50C 80C
20C or 30C
Why was Llewenllyns cup of tea cold 30 minutes after he made it?
Because a Hotter object’s heat always flow to a colder object i.e the air
Which direction does heat energy flow if is you are holding a snowball?
It flow from your hands into the snowball.
Which direction does heat energy flow if is you are holding a snowball?
It flows from your hands into the snowball.
How does conduction work?
As the particles get hotter the start to move. They then bump into each other transferring the heat.
Why do lots of layers keep you warmer in winter than on thick layer?
Because they trap air better and air is not a very good conductor of heat.
draw a Sankey diagram if 100J are put into a light bulb 80 percent is used as useful energy in light and twenty percent is added in heat energy.
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draw a Sankey diagram if 100J are put into a light bulb 80 percent is used as useful energy in light and twenty percent is added in heat energy.
Blank card. (check yourself for this one)
How does a thermal imaging camera produce images in the dark
infared is still produces even in the dark.
If you put food under a grill explain why it is not transferred through conduction and convection?
Because convection involves heat rising and it is not touching the grill?
A light bulb transfers 550J of energy into light and 50J inot heat. How much would be wasted and used if 1.2KJ were used.
1.1KJ would be used and 100J would be wasted.
Why is friction a problem for astronauts
because it heats up the tiles and can increase the temperature in the cockpit.
