Answer:
1. It has to do with gravity. ... That‘s also the reason why walking up stairs is so much harder than walking down stairs-when we go up, we have to work to overcome the force of gravity, while when we go down, the pull of gravity makes it easier for us.
2. Although the gravitational force the Earth exerts on the objects is different, their masses are just as different, so the effect we observe (acceleration) is the same for each. The Earth's gravitational force accelerates objects when they fall. It constantly pulls, and the objects constantly speed up.
3. Methods to increase or reduce friction - example
To reduce friction we can make the surfaces in contact smooth. Also adding a lubricant to two surfaces in contact reduces friction between them. Grease is added between the moving parts in machines, to reduce friction.
4. Friction is a force that occurs when two surfaces slide past one another. The force of friction opposes the motion of an object, causing moving objects to lose energy and slow down. When objects move through a fluid, such as air or water, the fluid exerts a frictional force on the moving object.
5. Friction can slow things down and stop stationary things from moving. In a frictionless world, more objects would be sliding about, clothes and shoes would be difficult to keep on and it would be very difficult for people or cars to get moving or change direction.
Explanation:
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