The resistance that one surface or object encounters when moving over another.a lubrication system which reduces friction’ It's originated from mid 16th century (denoting chafing or rubbing of the body or limbs, formerly much used in medical treatment): via French from Latin frictio(n-), from fricare ‘to rub’. Friction is the resistance to motion of one object moving relative to another. It is not a fundamental force, like gravity or electromagnetism. Instead, scientists believe it is the result of the electromagnetic attraction between charged particles in two touching surfaces.
Scientists began piecing together the laws governing friction in the 1400s, but because the interactions are so complex, characterizing the force of friction in different situations typically requires experiments and can't be derived from equations or laws alone.
For every general rule about friction, there are just as many exceptions. For instance, while two rough surfaces (such as sandpaper) rubbing against each other sometimes have more friction, very smoothly polished materials (such as plates of glass) that have been carefully cleaned of all surface particles may actually stick to each other very strongly.
The frictional force is that force responsible for wear and tear of two bodies. When two bodies in contact, move relative to each other then there exists a force which has a tendency to oppose that movement which is called frictional force. There are in general 2 different types of friction. Lets see about them.
1.STATIC FORCE
A static force refers to a constant force applied to a stationary object. A static force is too weak to move an object because it is being countered by equally strong opposite forces.
The most common example of a static force is static friction on a stationary object. If an object has some force being applied to it while it is on a surface, the force of friction will increase proportionally to the force until a certain limit. If the applied force is large enough, it can overcome the static friction and move the object. The force is then a kinetic force that is being resisted by kinetic friction
2. KINETIC FORCE
An object that has motion - whether it is vertical or horizontal motion - has kinetic energy. There are many forms of kinetic energy - vibrational (the energy due to vibrational motion), rotational (the energy due to rotational motion), and translational (the energy due to motion from one location to another). To keep matters simple, we will focus upon translational kinetic energy. The amount of translational kinetic energy (from here on, the phrase kinetic energy will refer to translational kinetic energy) that an object has depends upon two variables: the mass (m) of the object and the speed (v) of the object. The following equation is used to represent the kinetic energy (KE) of an object
We cannot see what is inside the event horiz
We basically understand what happens outside the black hole as you approach its event horizon, that infamous point of no return. The event horizon is where the escape speed exceeds the speed of light: you’d have to be going faster than light (which is impossible for any bit of matter) to escape the black hole’s gravity.
Inside the event horizon is where physics goes crazy. Calculations suggest that what the fabric of spacetime looks like inside a black hole depends on that particular black hole’s history. It might be turbulent, twisted, or any other number of things. One thing’s for sure, though: the tidal forces would kill you
According to theory, within a black hole there’s something called a singularity. A singularity is what all the matter in a black hole gets crushed into. Some people talk about it as a point of infinite density at the center of the black hole, but that’s probably wrong — true, it’s what classical physics tells us is there, but the singularity is also where classical physics breaks down, so we shouldn’t trust what it says here.
According to theory, within a black hole there’s something called a singularity. A singularity is what all the matter in a black hole gets crushed into. Some people talk about it as a point of infinite density at the center of the black hole, but that’s probably wrong — true, it’s what classical physics tells us is there, but the singularity is also where classical physics breaks down, so we shouldn’t trust what it says here.
Astronomers face an embarrassing conundrum:They don’t know what 95% of the universe is made of. Atoms, which form everything we see around us, only account for a measly 5%. Over the past 80 years it has become clear that the substantial remainder is comprised of two shadowy entities – dark matter and dark energy.
The former, first discovered in 1933, acts as an invisible glue, binding galaxies and galaxy clusters together. Unveiled in 1998, the latter is pushing the universe’s expansion to ever greater speeds. Astronomers are closing in on the true identities of these unseen interlopers.
Cells in the human body number in the trillions and come in all shapes and sizes. These tiny structures are the basic unit of living organisms.
Cells comprise tissues, tissues comprise organs, organs form organ systems, and organ systems work together in an organism. There are hundreds of different types of cells in the body and the structure of a cell is perfectly suited for the role it performs. Cells of the digestive system, for instance, are different in structure and function from cells of the skeletal system. No matter the differences, cells of the body depend on each another, either directly or indirectly, to keep the body functioning as one unit. The following are examples of different types of cells in the body.
1. STEM CELL
2. BONE CELL
3. BLOOD CELL
4. MUSCLE CELL
5. FAT CELL
6. SKIN CELL
7. NERVE CELL
8. ENDOTHERIAL CELL
9. SEX CELL
10. PANCREATIC CELL
11. CANCER CELL
Made from the seed of the cocoa tree, it is one of the best sources of antioxidants on the planet.
Studies show that dark chocolate (not the sugary crap) can improve your health and lower the risk of heart disease.
1. Very Nutritious
If you buy quality dark chocolate with a high cocoa content, then it is actually quite nutritious.
It contains a decent amount of soluble fiber and is loaded with minerals.
A 100-gram bar of dark chocolate with 70–85% cocoa contains:
11 grams of fiber
67% of the RDI for iron
58% of the RDI for magnesium
89% of the RDI for copper
98% of the RDI for manganese
It also has plenty of potassium, phosphorus, zinc and selenium
2. Powerful Source of Antioxidants
ORAC stands for “oxygen radical absorbance capacity.” It is a measure of the antioxidant activity of foods.
Basically, researchers set a bunch of free radicals (bad) against a sample of a food and see how well the antioxidants in the food can "disarm" the radicals.
The biological relevance of ORAC values is questioned, because it's measured in a test tube and may not have the same effect in the body.
However, it is worth mentioning that raw, unprocessed cocoa beans are among the highest-scoring foods that have been tested.
3. May Improve Blood Flow and Lower Blood Pressure
The flavanols in dark chocolate can stimulate the endothelium, the lining of arteries, to produce nitric oxide
One of the functions of NO is to send signals to the arteries to relax, which lowers the resistance to blood flow and therefore reduces blood pressure.
Many controlled studies show that cocoa and dark chocolate can improve blood flow and lower blood pressure, though the effects are usually mild.
4. Raises HDL and Protects LDL From Oxidation
Consuming dark chocolate can improve several important risk factors for heart disease.
In a controlled study, cocoa powder was found to significantly decrease oxidized LDL cholesterol in men. It also increased HDL and lowered total LDL for those with high cholesterol.
Oxidized LDL means that the LDL ("bad" cholesterol) has reacted with free radicals.
This makes the LDL particle itself reactive and capable of damaging other tissues, such as the lining of the arteries in your heart.
5. May Protect Your Skin From the Sun
The bioactive compounds in dark chocolate may also be great for your skin.
The flavonols can protect against sun damage, improve blood flow to the skin and increase skin density and hydration.
The minimal erythemal dose (MED) is the minimum amount of UVB rays required to cause redness in the skin 24 hours after exposure.
In one study of 30 people, the MED more than doubled after consuming dark chocolate high in flavanols for 12 weeks
6. Could Improve Brain Function.
The good news isn't over yet. Dark chocolate may also improve the function of your brain.
One study of healthy volunteers showed that eating high-flavanol cocoa for five days improved blood flow to the brain.
Cocoa may also significantly improve cognitive function in elderly people with mental impairment. It may improve verbal fluency and several risk factors for disease, as well.
Additionally, cocoa contains stimulant substances like caffeine and theobromine, which may be a key reason why it can improve brain function in the short term.
They are the fruit of the apple tree (Malus domestica), originally from Central Asia, and are grown all over the world.
Apples are high in fiber, vitamin C and various antioxidants. They are also very filling, considering their low calorie content. Studies show that eating apples can have multiple benefits for health (1,2,3,4)
They taste delicious on their own and are usually eaten raw, but they are also used in various recipes, juices and drinks.
There are many different types, with a variety of colors and sizes.
FACTS: for apple as per 100 grams
Amount
Calories 52
Water 86 %
Protein 0.3 g
Carbs 13.8 g
Sugar 10.4 g
Fiber 2.4 g
Fat 0.2 g
Saturated F 0.03 g
Monounsaturated 0.01 g
Polyunsaturated 0.05 g
Omega-3 0.01 g
Omega-6 0.04 g
Trans fat 0 g
Fiber 2.4 g
Fat 0.2 g
Saturated F 0.03 g
Monounsaturated 0.01 g
Polyunsaturated 0.05 g
Omega-3 0.01 g
Omega-6 0.04 g
Trans fat 0 g
(enzymes are made by RER) to digest the worn-out cell organelles. When the cell
gets damaged, lysosomes may burst and the enzymes digest their own cell, hence
called as “Suicidal bags of a cell”. It is a waste disposal system of the cell.
A lysosome is a membrane-bound organelle found in nearly all animal cells. They are spherical vesicles that contain hydrolyticenzymes that can break down many kinds of biomolecules
Lysosomes are surrounded by a membrane composed of phospholipids that separate the inside of the lysosomes from the membrane's external environment. Phospholipids are the same cellular molecules that make up the cell membrane surrounding the entire cell. Lysosomes range in size from 0.1 to 1.2 micrometers.
What is friction?
The resistance that one surface or object encounters when moving over another.a lubrication system which reduces friction’ It's or...
