Answer the following questions. 1. Why are heavy objects moved using rollers? 2. Why are sand and gravels spread on wet ground? 3. Why do birds and fish have a streamlined shape? 4. What do you mean by lubrication? 5. Why do trekkers have spikes on the soles of their shoes?
Answers
Answer:
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Explanation:
1) When it comes to moving big things, rollers are a time-tested solution. By breaking the gravitational bond between two surfaces (by being placed between the objects), rollers reduce friction—allowing seemingly unmovable objects to easily be moved from one point to another
2) When it rains, the water on a road causes a loss of friction. As tires move over a wet surface, the water fills in the tiny pits in the road surface, effectively smoothing out the surface. As a result, the normal heat and friction created is decreased, leading to a surface that is more slippery than when dry.
3) Birds have streamlined body so as to reduce the air resistance during flying. Whereas fishes have streamlined body so as to reduce friction in water and help them to move faster.
4) lubrication is the control of friction and wear by the introduction of a friction-reducing film between moving surfaces in contact. The lubricant used can be a fluid, solid, or plastic substance. ... Many different substances can be used to lubricate a surface. Oil and grease are the most common.
5) Spikes increase the surface of the shoes & make it rough which results in an increase in friction. This helps to have more grip on the floor and chances to slip reduces. This makes it easy for sportsmen to walk or run as their grip on the ground increases.
hope it helps :)
Answer:
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