Small drops of liquids tend to be spherical because of their surface
tension. Surface tension is the result of intermolecular attracting
forces. When you put a small drop of a liquid on a solid surface, the
inermolecular forces of the solid surface will tend to attract the liquid
molecules. Depending on the magnitude of the different forces, the solid
surface will present certain degree of 'wettability'. If you compare how
a drop of water sits on a clean penny and on a penny that you rubbed
with your fingers, you'll notice that the drops contact angle differ.
The drop on the clean penny will cover more contact area (more wettable
surface) than the drop on the 'oily' penny (less wettable surface). Oil
reppels water because the intermolecular forces between the water and
oil molecules are very weak compared to the intermolecular forces between
similar molecules.
Now, water intermolecular forces are paricularly strong, and so the drop
of water on the penny will resist more than the oil molecules to be spreaded
on the surface of the penny. Oil drops tend to wet more the surface of the
penny and will tend to occupy more area. And so you'l get fewer oil drops
on the penny's surface.
Approximately 30 to 35 drops of water can fit on a US penny before spilling over. The surface tension of the water allows it to form a dome-like shape on top of the penny, holding more drops than you might expect.
The heads side of a penny holds more water because it has a slightly raised edge that creates a small barrier preventing the water from spilling over the sides. The tails side is flat and the water can easily spill off the edges.
Because the hydrogen molecules in water want to stay connected and once you add soap it messes with the bonds and and they don't stay bonded as strongly. Also the mass and density of the water changes when you add soap.
Some pennies may hold more water than others due to variations in surface tension caused by differences in cleanliness or wear on the penny's surface. A clean penny may have a lower surface tension and allow water to spread more easily across its surface, while a dirty or oxidized penny may have a higher surface tension, causing the water to bead up and be contained in a smaller area.
Dish soap is more effective at cleaning a penny than water alone. Dish soap can break down oils and dirt on the surface of the penny, allowing for a more thorough cleaning compared to just using water.
for example, if drops of water are placed on the top of a penny, the surface tension is going to hold the drops on top of the penny. when the penny can hold no more, it will all overflow. make sense?
Water has a surface tension. When dropping water on a penny, people usually underestimate how much water the surface of a penny can hold. The surface tension of water is strong on a smaller surface, and when dropping water on the surface of a penny, towards 20 drops the water on the penny will look like it is bulging out a lot. It really depends, depending on which side of the penny you are using, it ranges from 6 to even 34 drops using a simple eyedropper. Because eyedroppers do not produce the exact same size of drops every time, the result is not very accurate. To be even more accurate, scientists use accurate distributing machines and a very new penny to determine how many drops of water it can hold without vibrations. There could be certain amounts of grime and dirt on a penny, depending on how old it is, which can affect how much water can be put onto it. Different types of water can also change how much a penny can hold. Tap water has certain amounts of chemicals in it, and that could also affect the weight and surface tension of the water on the penny. The height of which the water comes off from matters too, the more force of the water that comes down, the more likely the water on the penny is to splash and spill. The place the water lands on also has an effect on it. To be even more accurate, light has a mass. If light shines directly at the water on a penny, it could push it a tiny bit. This change is impossible to see, and it has basically no effect on the penny or water at all whatsoever. Remember, all tests may not be 100% accurate, and there may always be a chance that there is a better way to make a penny hold more droplets of water than the presumed "most advanced and accurate" way.
Approximately 30 to 35 drops of water can fit on a US penny before spilling over. The surface tension of the water allows it to form a dome-like shape on top of the penny, holding more drops than you might expect.
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Yes, the amount of soapy water can affect how many drops fit on a penny. More soap can reduce the surface tension of the water, allowing it to spread and form a flatter shape, which may result in fewer drops fitting on the penny. Conversely, less soap increases surface tension, potentially allowing more drops to fit. Therefore, the concentration of soap in the water plays a significant role in this experiment.
Soapy water will hold more on a penny compared to pure water. This is because the surface tension of soapy water is lower than that of pure water, allowing it to spread out more and cover the penny's surface.
When you place regular water on a penny, surface tension allows you to fit about 15-20 drops before it overflows. However, when you add soap to the water, the surface tension decreases, allowing more water to spread out rather than bead up. As a result, you can typically fit around 10-15 drops of soapy water on the penny, demonstrating the effect of soap on water's surface properties.
It all depends on if you drop the water fast or if you drop it slow. Ideally, everyone performing the experiment would include the following: - distilled waterThere are a lot of factors involved. The cohesion and adhesion ('stickiness') of water molecules can be effected by things like oils (on surface pennies from peoples' skin) and other contaminates on the penny. The size of the dropper or pipette will determine the size of each water droplet - the larger the drop, the fewer number of drops will fit on the penny. The manner in which the water is added to the penny is also a factor. Water has a cohesive nature (the molecules are kind of like magnets and are attracted to one another). Therefore, if the drop from the pipette is allowed to touch the water already on the surface of the penny, the water can be 'pulled' out of the dropper. When this happens, the size (volume) of the drop is not always the same - it could be a very small amount (which will result in a very large number of drops), or a large amount. Soap causes the cohesiveness ('stickiness') of the water molecules to decrease so they are not as strongly attracted to each other. Because of this, when soap is added to the water the number of drops that can be placed on the penny will decrease. The water molecules can't 'stick' together as well, so the water on top of the penny spills off sooner than it would with non-soapy water. Ideally, everyone performing the experiment would include the following: - distilled water (to start with) - same type/size of calibrated dropper/pipette - same date of penny - penny cleaned as thoroughly as possible using same cleaning procedure - same 'dropping' procedure
There are two factors that we see in water, it's adhesive and cohesive abilities. Better put, it's the ability for water to stick to surfaces as well as stick to itself. This gives an overall "surface tension" that will develop as the bead of water grows. This amount of mass and volume will get too great, however, and the water will no longer be able to hold itself together. If you wanted to lower the surface tension, adding soap would make it so that the water would break after fewer drops.
The heads side of a penny holds more water because it has a slightly raised edge that creates a small barrier preventing the water from spilling over the sides. The tails side is flat and the water can easily spill off the edges.
an eraser. a penny would catch more air under it. no both would drop at same speed
Water has a higher surface tension than rubbing alcohol, which allows it to form a more cohesive droplet that can hold together better on the surface of a penny. Additionally, water is more polar than rubbing alcohol, leading to stronger adhesive forces between the water molecules and the penny's surface. This results in water being able to "stick" and accumulate more effectively than rubbing alcohol.