AIR PRESSURE WHAT IS AIR PRESSURE Pressure is

AIR PRESSURE

WHAT IS AIR PRESSURE? • Pressure is the force on a certain area • Air pressure is the force exerted by the weight of a column of air on a given surface • The weight of the atmosphere on your palm is roughly the weight of a washing machine

WHY AM I NOT CRUSHED? The air pressure pushing IN outside your body is balanced by your internal fluid pressure pushing OUT.

ON THE MOON • Know what you know regarding air pressure, why must astronauts were pressurized suits on the Moon? • In the video clip you saw, a scientist says that astronauts would be in big trouble if they tripped, fell and cracked their helmet. What would happen to the air pressure inside their suit then? • What do you think would happen to a human body in a vacuum?

• It depends on how much air is above, the more air above, the higher the pressure and density • At the bottom of the atmosphere, air is densest, thus air pressure is the highest. • At the top, air is the least dense with the lowest pressure

AIR PRESSURE ACTIVITY • Go get your lab book!

• Purpose: The purpose of this activity is to WRITE see the effect of air pressure THIS ON • Materials: candle (1 or 3), beaker, petri YOUR dish, water, clay BOOK: • Procedure: – Fill petri dish ¾ of the way with water – Place candle(s) in the clay so it stands in the water – Once the candle is lit, quickly lower the beaker over the candle – Observe what happens when the candle extinguishes – Measure the height of the water – Repeat this 2 more times

DATA TABLE: ______ CANDLES Trial 1 2 3 average Average of other group. _______ candles Height of Water (cm)

CONCLUSION • Answer these following questions for homework • When the air inside the beaker cooled, did the pressure in the beaker increase or decrease? • What did the air pressure OUTSIDE the beaker do to the water? • Compare the height of the water in the 1 candle to the 3 candle experiments. • Did the number of candles make a difference? • Why is the air pressure at sea level different from air pressure high up in the atmosphere?

• For the next activity: bring a CLEAN tin can.