Answer: B. meteorites, UV rays
The earth's atmosphere plays an important role in shielding the space rocks and meteorites enters inside the earth due to collision with the celestial body. Due to high heat and pressure in the mesospheric layer of the atmosphere these meteorites burned up before reaching the biosphere or hydrosphere system of the earth. The UV rays are protected from entering into the earth atmosphere by the ozone layer present in the stratosphere of the atmosphere. Both meteorites and UV rays can negatively effect the human population. Therefore, the atmosphere is an agent which provides protection against them.
Answer:
m = 0.4 [kg]
Explanation:
Weight is considered as a force and this is equal to the product of mass by gravitational acceleration.
where:
W = weight = 0.8 [N]
m = mass [kg]
g = gravity acceleration 2[N/kg]
Therefore:
![m=W/g\\m = .8/2\\m = 0.4 [kg]](https://tex.z-dn.net/?f=m%3DW%2Fg%5C%5Cm%20%3D%20.8%2F2%5C%5Cm%20%3D%200.4%20%5Bkg%5D)
Answer:
Explanation:
Monosaccharides are the simplest form of carbohydrates which are called as single sugars. These are the building blocks of bigger carbohydrates.
Disaccharides are the sugars that are formed when two monosaccharides combine together by glycosidic bonds.
Polysaccharides are the long chains of carbohydrate molecules. These are formed by the monosaccharide units bonded by the glycosidic linkages.
The insulin and glucagon are the two hormones secreted by the pancreas that regulate the blood glucose levels. Insulin is secreted by the beta cells of pancreas. It is secreted when the blood glucose level is high. Glucagon is secreted by the beta cells of pancreas when the blood glucose level is low.
At critical temperature, the resistivity of the superconductor
B. It suddenly drops to zero
Explanation:
Materials can be classified into three different types depending on their resistance:
- Conductors: these materials have generally low resistance and allow electricity to pass through easily. The resistance of a conductor increases linearly with the temperature
- Insulators: these materials do not allow electricity to pass through - so they have very high resistance
- Semi-conductors: these are materials that are insulators are room temperature, however they becomes conductors when heated. Therefore, the resistance of a semiconductor decreases when the temperature increases
- Superconductors: these are special materials that are normally conductors; however, at very low temperatures (we are talking about temperature very near to 0 K), their resistance becomes suddenly zero.
Therefore, the correct answer is:
B. It suddenly drops to zero
Learn more about current and resistance:
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On the floor because the force from the train moving and she wouldn't be able to catch it in time
