Word limit - 73 words
Explain why sportsmen use shoes with spikes.
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Word limit - 150 words
Describe the green house effect in your own words.
Explain how you can take care of your eyes.
Suggest three measures to protect ourselves from lightning.
Explain some examples where we have to reduce the friction.
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Answers
Question - Explain why sportsmen use shoes with spikes.
Answer - Yes, it is absolutely correct that the sportsmen use shoes with spikes. It is because of a reason that these spikes within the shoes give them(sportsmen) a better grip while running on the floor and for safe movement too. This is because the force of the friction between the shoes and the ground increase with the help of spikes.
Question - Describe the green house effect in your own words.
Answer - Greenhouse effect ► The most important reason of greenhouse effect is increasing of carbon dioxide. And the second reason is global warming i.e., global warming as the name suggest is the increase in temperature of the globe i.e., the average temperature of the atmosphere has increased. Few gases like carbon dioxide, methane, ozone are responsible for it. The quantity of these gases, is increasing day by day in the atmosphere. If it is not stopped then it be more increased and start global warming.
When the infrared rays that are coming from the sun, come to the surface of the earth then some of the rays are get absorbed on the earth's surface and some of them are reflected back to the atmosphere, there these rays are react with carbon dioxide and the water vapours, then our earth became heated and that's all greenhouse effect!
Question - Explain how you can take care of your eyes.
Answer - 25 cm is the perfect and comfortable distance at which a person can read with normal eye. Some persons are not able to see close things and are known as hypermetropia and some are not able to see that are far away and as known as myopia. So it's important for everyone to take care of their eye. Some are the reasons that how can we take care of our eyes ►
❶ We should have to wash our eyes properly with clean water daily.
❷ We should have to eat vitamin A rich food for healthy eye.
❸ Never look directly at the sun, because sun rays are very harmful to our eyes.
❹ Never look directly the sun on solar eclipse too.
❺ Use sunglasses on hot summer day.
❻ Never read any book or never read anything on mobile or else in a running vehicle it is also not good for eyes.
❼ Never rub eyes.
❽ Never study in very high light or very low light too.
❾ If advised by the eye specialist then use suitable spectacles.
❿ Read at that distance which is normal i.e., 25 cm.
Question - Suggest three measures to protect ourselves from lightning.
Answer - Firstly let us know something about lighting! Lighting is caused due to the electric discharge between the clouds and the earth. We can also say that, it is that process of electric charge between different type of clouds. And then lighting is caused.
Some measures to protect ourselves from lightning are mentioned below ►
❶ During lightning actually, none place that is open is not safe ever. That's why never go in open place whenever you saw lightning or hear thunderstorm.
❷ Wherever you are in inside any place and you hear a thunderstorm never come outside at this spot wait until some minutes till lighting is stopped and you are not hearing thunderstorm too.
❸ If you are travelling in a bus, car then it's good if you close its doors and windows because that time you are absolutely safe.
❹ If you are in outside place then never take shelter under trees, electric poles or other metal objects, stay away from them.
❺ Don't lie on ground, instead of this squat low on the ground floor means place your hands on your knee with your head between the hands.
❻ Never bath whenever it is lightning
❼ Don't came in the contact of metal objects.
❽ Unplug electric appliances such as television, computer, fridge etc.
Question - Explain some examples where we have to reduce the friction
Answer - Sometimes there is a need to reduce the friction. Let's see when there is a need ti reduce it but firstly let's see about this topic properly.
Friction? Friction opposes the relative motion. It opposes motion between two surfaces that are in contact to each other. Friction act on both of the surfaces. It depends how hard the two surfaces press together. Friction depend on the nature of surfaces in contact.
Causes of friction? Every surface however it is smooth or rough/irregular in the form of depression or projection. When a surface tend to move over the other then the irregularities interlock with each other and this cause friction.
Factors affecting friction? There are many factors that affect friction let's see what are they!
❶ The normal force with which the two surfaces are pressed.
❷ Area of contact.
❸ Nature of the two surfaces in the contact.
Now let's see examples where we have to reduce the friction ►
We use oil to reduce the friction between the moving parts inside a car engine. Same process we do with machines
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★ Question : Explain why sportsmen use shoes with spikes.
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★ Solution : Sportsman use shoes with spikes to increase the force of friction between the shoes and the ground. The increased force of friction give them a better grip while running.
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★ Question : Describe the green house effect in your own words.
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★ Solution : The greenhouse effect is a phenomenon when the earth acts like a greenhouse trapping the solar radiations which are supposed to be reflected back to the atmosphere. These radiations are trapped by some gases like methane, carbon dioxide and water vapours, which are found excessively due to air pollution. So, this results in global warming.
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★ Question : Explain how you can take care of your eyes .
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★ Solution : To protect our eyes, the given points should be taken into account :
(1) Visit an eye specialist regularly.
(2) Avoid reading in dim light and very bright light.
(3) Avoid direct exposure of sun light to the eye.
(4) Clean your eyes with cold water quickly if dust particles or small insects enter your eye. Do not rub your eyes.
(5) Maintain a distance of at least 25 cm between the book and your eyes while reading.
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★ Question : Suggest three measures to protect ourselves from lightning.
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★ Solution : Some of the measures to protect ourselves from lightning are as follows:
(i) We should stay in a completely closed place.
(ii) We should avoid standing in open during thunderstorm
(iii) If moving in a car, we should remain there until the lightning is over and close the windows.
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★ Question : Explain some examples where we have to reduce the friction.
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★ Solution : Ball bearings are also used to reduce friction. Ball bearings change sliding friction to rolling friction. This is a very useful thing to do since rolling friction is much smaller than sliding friction. Ball bearings are used in most mechanical structures which have moving parts. Small metal balls made of stainless steel, brass, ceramic, etc., are placed between moving surfaces (the surfaces . can be flat or cylindrical) to reduce friction.
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