Upside-down water cup Follow FizzicsEd 150 Science Experiments: Comments 4 You will need: One cup of water full to the brim with water. One piece of card, larger than the cup rim. You can also use paper. An area that you can get wet. Written by Fizzics Education. Reviewed by Ben Newsome CF. Cite this experiment Copyright Notice Instruction Video Instruction 1 Fill your cup with water (try different levels each time!). Gently place a dry card on top of the cup, making sure there is good contact over the cup rim. If doing this inside have a tray, bowl or plate to catch the water spilling 2 Carefully turn the cup upside down, keeping upward pressure on the card with your hand. When the cup is upside down, let go of the card. Can you explain why the water doesn’t come out? 3 School science visits since 2004! – Curriculum-linked & award-winning incursions. – Over 40 primary & high school programs to choose from. – Designed by experienced educators. – Over 2 million students reached. – Face to face incursions & online programs available. – Early learning centre visits too! 4 Online courses for teachers & parents – Help students learn how science really works 5 Get the Unit of Work on Pressure here! Want to dive into air pressure? Get the 60-minute video + PDFs + curriculum links for your class here! How to turn a cup of water upside down with no spills from Fizzics Education on Vimeo. Why Does This Happen? The Science of the Upside Down Water Cup Air molecules are constantly pushing into everything, in every direction imaginable. This is known as atmospheric pressure. To give you an idea of its strength, if you look at your thumbnail, you have the equivalent of around 1 kg of weight pushing down on that body part alone! When you flip the cup, there is very little air inside (if any), meaning the downward force inside the cup is coming only from the weight of the water. Depending on the size of your cup, the water might weigh around 250g. However, the air below the card is pushing upwards with the full force of the atmosphere. Because the upward air pressure is significantly greater than the downward pressure of the water, the card is held firmly against the rim, keeping the water inside the cup. Applications Understanding how pressure works allows engineers to design incredible structures. Airlocks, for example, allow deep-sea divers to leave and enter submersible vehicles while completely underwater. By compressing the air inside the airlock to equalise with the water pressure outside, engineers can stop the ocean from rushing in. NASA even uses these principles during underwater training to simulate the vacuum of space! Variables to test Find out more on variables here. Volume and Mass Try progressively larger cups. How much water can the air pressure support? Try a bucket (with a very sturdy piece of card!). Liquid Density Does it matter which type of liquid is used? Try liquids of different densities, like oil or salty water. Does a heavier liquid make the card fall sooner? Seal Integrity What happens if you use a mesh screen instead of a solid card? (Hint: Look up “Surface Tension Water Cup” to see how water can stay in even without a card!) âś… Reviewed: April 5, 2026 APA 7 Citation: Fizzics Education. (2018). Upside down water cup. https://www.fizzicseducation.com.au/150-science-experiments/water-science-activities/upside-down-water-cup/ Copy APA Citation Reviewer This resource was last reviewed for scientific accuracy on April 5, 2026. Ben Newsome CF is the recipient of the 2023 UTS Chancellor’s Award for Excellence and a Churchill Fellow. He is a global leader in science communication and the founder of Fizzics Education. Learn more! Teaching about air pressure? Check out the Flight or Weather show! Teaching about Newton’s laws? Check out the Forces, Friction & Movement workshop! Get in touch with FizzicsEd to find out how we can work with your class. Forces, Friction & Movement Years K to 6 Maximum 30 students School workshop 60 or 90 minutes Online Class Available Read More Enquire Now STEM Full Day Accelerator - Primary Designed from real classroom experiences, this modular day helps you create consistently effective science learning that directly address the new curriculum with easily accessible and cost-effective materials. Read More Enquire Now Be Amazing! How to teach science, the way primary kids love. $29.95 excl. GST View Details Add to Cart Trustpilot
Fill your cup with water (try different levels each time!). Gently place a dry card on top of the cup, making sure there is good contact over the cup rim. If doing this inside have a tray, bowl or plate to catch the water spilling
Carefully turn the cup upside down, keeping upward pressure on the card with your hand. When the cup is upside down, let go of the card. Can you explain why the water doesn’t come out?
School science visits since 2004! – Curriculum-linked & award-winning incursions. – Over 40 primary & high school programs to choose from. – Designed by experienced educators. – Over 2 million students reached. – Face to face incursions & online programs available. – Early learning centre visits too!
Get the Unit of Work on Pressure here! Want to dive into air pressure? Get the 60-minute video + PDFs + curriculum links for your class here!
Teaching about air pressure? Check out the Flight or Weather show! Teaching about Newton’s laws? Check out the Forces, Friction & Movement workshop! Get in touch with FizzicsEd to find out how we can work with your class.
Forces, Friction & Movement Years K to 6 Maximum 30 students School workshop 60 or 90 minutes Online Class Available Read More Enquire Now
STEM Full Day Accelerator - Primary Designed from real classroom experiences, this modular day helps you create consistently effective science learning that directly address the new curriculum with easily accessible and cost-effective materials. Read More Enquire Now
Designed from real classroom experiences, this modular day helps you create consistently effective science learning that directly address the new curriculum with easily accessible and cost-effective materials.
Be Amazing! How to teach science, the way primary kids love. $29.95 excl. GST View Details Add to Cart Trustpilot
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