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6

As mentioned in the comments, this is an instance of supercooling. When you cool a liquid below its freezing point, the molecules are still moving around quite a lot and any two that stick together are likely to be broken up by a subsequent impact. Liquids freeze better when the molecules have something to latch onto -- either a block of the same ice they ...


3

If you or one of your friends has transition lenses for their glasses, then you can test the UV blocking ability with those. The transition to darker shades in these lenses is initiated by UV-light. So hold your sunglasses over some transition lenses and see if they start to turn darker. You can try this with any photochromatic material really, but ...


-2

Most likely is its always hotter than the outside. the frames absorb heat up into the 160 plus mark depends on where you live. 100 degrees usually about 150 degrees gained we call it solar gain.


0

if it was a plastic cola bottle it is because the plastic is a cross linked polymer, and is designed to be heated and then pressurized into a mold, and cooled under pressure to maintain its shape. this particular plastic was chosen because of its low failure rate in this process ( holes and deformities ) it is very much the same as heat shrink tubing or ...


0

A certain minimum force is needed to move the wheels. If you move your body slowly, you can move forwards (or back) on the chair without the chair moving. But if you make a sudden move, the force you exert on the chair (and that the chair exerts on you) is greater than this minimum. This means you can move by using a different acceleration in the forward ...


0

Maybe the air because of the Radon: https://en.wikipedia.org/wiki/Radon#Domestic-level_exposure


-1

That banana is a real radiator!


0

Ice particles in the atmosphere deflect the path of light rays by refraction. Many ice particles are shaped like hexagonal prisms, and the most common angle of deflection through an ice hexagon is 22 degrees (there is a diagram on the "22 degree halo" Wikipedia page). Most of the deflected light rays will not reach your eyes - you will only see the ones ...


10

In a sense, wax does not burn, at least not in the same way that, for instance, magnesium burns. Instead wax gets hot and vaporizes, and the vaporized wax is what burns. The heat of combustion vaporizes more wax, and the process continues. A candle wick works by forming a conduit for the pool of melted wax which forms around the base of the exposed wick. ...


1

I tested it against a control and it worked. Used longneck glass bottles. Didn't measure the difference but the difference was notable to the touch after half an hour.


5

Let's take this in steps. First - assume there is zero friction between the bottom block and the tower, and between the bottom block and the ground. If I move the block "infinitely quickly" the tower will have had no time to tilt at all, and it will drop vertically (and remain upright). This tells me there are two things to consider: the time take to ...


3

The glue used on plastic bottles is usually based on polyisobutylene or something similar to it. This has long hydrocarbon chains in it, and when the material is at equilibrium the polymer chains form a tangled network much like a mass of tangled wool. If you quickly stretch the polyisobutylene then the chains cannot untangle themselves because the ...


0

I would assume the difference between the string and the glue is that the tendency to achieve minimum surface energy in the glue case. The glue shrinks in length so that it can decrease in surface area, while the string need not since it does not have a particular tendency for minimum surface energy.


2

The lower speed limits are mainly determined by how fast a car needs to be able to stop. In town there are lots of children around, and you need to be able to stop quickly if a child runs into the road, so the speed limit in towns is low (30 mph in the UK). Where the risk is especially high, e.g. near schools, it's not uncommon for the speed limit to be ...


4

Very roughly speaking, the danger to a living being riding in a crashing car is that of forces that arise within living tissues when that being is forced to change direction swiftly (being bumped in a sideswipe) or to stop suddenly. Those forces tear and injure living tissue. The physics and biophysics content of speedlimits is of setting states of motion on ...


4

Curved roads are banked so that less transverse traction is required to prevent a vehicle from slipping. In some parts of the US (and perhaps elsewhere), there are "advisory" speed limit markings near tight turns, which are loosely related to safe speed allowed by the banking of the turn. Here's an example where the "ramp" limit is lower than the highway ...


1

When plastic bottles are made they start with something that looks like a test tube with the threaded top for the bottle cap. It's heated and air is blown into it while it sits in a bottle shaped mold. Then it's quickly cooled to lock the plastic into that shape. The stretching creates residual stress in the plastic. It wants to un-stretch like a taught ...


1

Let's solve this in two parts. First, I will calculate how fast you need to go at the bottom of the swing in order to be able to make a complete loop (without the rope going slack). Next, I will estimate whether you can achieve this speed by "pumping" - that is, moving your center of gravity around to increase your speed. Part 1: speed needed The velocity ...


1

If you think of the runner as being stationary and the ground as being the thing that moved, you can think of a rock hitting a rigid object off center. A torque is imposed on the body based on the force perpendicular to the body and the distance from it's axis of rotation.


0

Let's assume that the rain is pretty consistent in the interim you have to go between two points. Your front side absorbs most of the water as you move along the path. Every moment you're moving, your shirt gets some water in it. The water density of the environment is pretty consistent now, so if you move faster, you trace out a larger volume differential ...


1

When you move with a certain velocity, you possess what is known as inertia of motion which is the measure of the difficulty to avert the motion. Since you have velocity, you have an associated momentum. Now, when your foot gets struck to the stone, by Newton's third law, the stone exerts a reactive force due to its deformation by the force applied by you. ...


0

The double slit experiment is easy to realize. I did it the first time following instructions from the Mickey Mouse Magazine. Else if you consider that having at least three polarizers leaves and one flashlight at home is normal , there is the well documented three-polarizers 'paradox'. It needs some concentration from general public. For attention purpose, ...


0

A will lose heat faster. Conduction and convection scale as the temperature difference, which is almost twice as large for A as for B. The warmer water in A will also evaporate faster, removing more heat as it does.


1

A Fluorescent lamp ballast provides a spike of high voltage that starts electrons flowing from one electrode to the other. After ignition, once an arc of electrons is flowing through the gas, the voltage requirement drops significantly as current begins to pick up on its own. The function of the ballast is to regulate voltage from high at startup to low ...


0

Apparently, that's a myth. If I had to guess, I'd say it comes from people assuming it's the same for all types of bulbs. (That, or poor quality of the bulb) See: http://sustainability.stackexchange.com/questions/54/what-s-the-best-strategy-for-turning-off-cfls-that-will-save-energy-but-not-redu for more details


5

See this research conducted in Princeton. To summarize their research, they found that it's related to how batteries generate electricity. It's generated by a chemical reaction inside the batteries, as zinc turns to zinc oxide. The zinc oxide starts to cover the outside of the battery, and is a bouncier material, and this creates the bounce. (Also, in many ...



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