When he gave to the wind its weight and apportioned the waters by measure,
Air Has Weight and Temperature Affects It? LESSON THEME This lesson has two activities that develop a basic understanding about the weight of air and its basic importance to understanding meteorology and to determine that a change in temperature of air affects its vertical movement. OBJECTIVES Students will • Experiment with the change in the position of a bar balancing a balloon inflated with air on one end and a noninflated balloon on the other end and the cause for this change • Write a procedure for investigating a research question • Identify factors affecting the dynamics of air in motion
To begin these air pressure experiments wave your hand back and forth in the air. It's easy to move your hand around because air pressure is pressing onto your hands in all directions. Air actually weighs 14.7 pounds per square inch at sea level. That means that every square inch of your body is being pressed on by 14.7 pounds of pressure.
Ruler(stick or clothes hanger may also be used
Needle or sharp pin
Cut three strings approximately 12 inches long.
Blow up two balloons so they are the same size. Tie a string to each balloon.
Tie one of the balloons to each end of the ruler tight enough so the string will not slip.
Tie a string loosely around the center part of the ruler so that you can slip the knot back and forth until the balloons are balanced.
Tape the string in place so it will not move when the balloon is deflated. Prick one of the balloons with a needle or sharp pin.
Watch how the ruler moves upward on the side where the balloon was deflated. If this does not happen it might be because the center string was not tight enough and moved when the balloon was deflated.
Try the experiment several more times to see if the experiment works consistently. This is the way real scientists do their work. They test their hypothesis several times to make sure the same thing happens consistently.
Extending the experiment
Try these air pressure experiments. Balance two deflated balloons on a ruler or stick. Take one balloon off the stick and inflate it. Return the balloon to see what happens. Try balancing several balloons on a yard stick. When you have the yardstick in balance. Predict what you think will happen if you deflate all the balloons, one at a time, from left to right. After writing down your prediction, try this air pressure experiment.
Science behind the experiment
Air is a real substance and it has weight. That is why it weighs 14.7 pounds per square inch at sea level. What scientists mean when they give this figure is that if a column of air one square inch in size from sea level to the top of the atmosphere above Earth would weigh 14.7 pounds.
If you travel up over a mountain pass air pressure decreases as you move upward. At 18,000 feet above the Earth the air pressure is approximately 7.35 pounds per square inch or half the atmosphere at sea level.