Cohesion

The ‘Am I Dense’ experiment

The 'Am I Dense' experiment In our floating experiment, we touched on the topics of buoyancy. But in reality, flotation is also affected by other scientific principles as well. Here, let Reeko Pour one-third cup of syrup into the glass jar. Now pour one-third cup of cooking oil into the jar. Finally, pour one-third cup of water into the jar. Let the contents settle for a few minutes. Drop a piece of plastic, a grape, and a small cork into the liquid. Notice how the objects you dropped in settle down to different layers of the mixture. The liquids have different densities. The most dense (syrup) will be at the bottom, the least dense (oil) will be at the top, with the water in between.…
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Cohesion

Super bouncing bubbles science experiment

Super bouncing bubbles Reeko loves bubbles - all kinds of bubbles. Reeko loves chomping a big glob of bubblegum and blowing bubbles the size of baseballs (and as a kid, used to giggle with glee as his mother struggled to cut the gum from his hair). Reeko loves making bubbles in the bathtub using the "natural" bubble-maker method (if you haven't mastered the natural bubble-maker method, eat beans, it helps). And of course, the science behind bubbles is quite amazing too. Bubbles that you find in liquids are simply air that is trapped inside the liquid. Soap bubbles work on the similar principle but with a bit more complexity. The surface area of a liquid, like water, has a certain "surface tension". Surface tension makes…
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Cohesion

Sticky water

The stickiness of water experiment Yep, it' true. Water has a certain 'stickiness' to it. Read Make five holes in the side of the can (using the nail). Make sure the holes are made near the base of the can. Fill the can with water. Pinch the streams of water together with your thumb and finger. The streams of water are held together by the water's "stickiness," or surface tension. Surface tension is the tendency of the surface of a liquid to behave as though covered with a skin. This is due to the cohesive forces between the molecules at and near the surface. Not sure what's going on here? Check out the instructions here! Experiment Supplies Supplies: Coffee can
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Cohesion

Rocket powered pennies

Rocket powered pennies Remember - heat causes things to expand (or get larger). Cold causes things to contract (or get smaller). Heating an object sealed inside another object can produce some interesting results. Let's demonstrate with this experiment. Take an empty soda bottle and place it in the freezer for about 1 hour. Take the bottle out of the freezer. Wet the top and place a penny on the top so that it covers the mouth of the bottle (there should be no air leaks). Place the bottle back in the freezer for at least another hour. Take the bottle out of the freezer and grasp the sides with both hands. Hold the bottle tight and wait. Were you surprised? Placing your hands around the…
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Cohesion

Frightened run-away pepper

Frightened run-away pepper We all know how glue or tape can be used to stick two objects together. These adhesives cause the two objects to cohere (or adhere) together. Cohesion is the word for this sticking force. Cohesion also occurs on common everyday objects - rain to a car's windows, dust to the ceiling fan, chewing gum on Mom's carpet. This experiment demonstrates cohesion in an interesting situation - and Mom's carpet stays looking as good as new! Fill a dish with water. Sprinkle some pepper on top of the water. Now drop several drops of dishwashing detergent in the center of the water. Pretty cool, huh. What happens to the pepper? Notice how the effect only occurs in the middle of the water. The…
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