Hot air is Lighter than cold air lab activity with Aim and material required and procedure and observation and conclusion
Answers
Answer:
What to do:
. put the balloon onto the mouth of the narrow bottle so no air can get in or out
. get an adult to help you pour hot water into one jar, and pour cold water into the other jar. Only fill them half-way, so they don't overflow in the next step.
. put the bottle with the balloon on it into the jar of hot water, and watch what happens.
. now put the bottle with the balloon on it into the jar of cold water for a few moments, and wait for the result (ice cubes will hurry it up)
What's going on:
When you put the bottle with the balloon into the first jar, the hot water heats up the air in the bottle and makes it expand. (Gases always expand when they're warm - the heat gives the gas energy to spread out more). The expanding gas blows up the balloon.
When you put the bottle into cold water, the air cools down again. Cool air hasn't got as much energy, so it shrinks - and the balloon shrinks with it.
What's it got to do with hot air balloons?
We just saw that hot air expands, and cold air shrinks. So hot air must be less dense than cold air.
Things that are less dense float on top of things that are more dense, so hot air always floats on cooler air. And hot air balloons will always float on cooler air. (Unless someone's got a giant balloon-sized skewer).ation: