STATE and explain, with example ,how friction can help the cause of motion in certain dituaions
Answers
Answer:
Introduction
Friction is a force that opposes motion between any surfaces that are touching. Friction can work for or against us. For example, putting sand on an icy sidewalk increases friction so you are less likely to slip. On the other hand, too much friction between moving parts in a car engine can cause the parts to wear out.
Friction between the graphite in a pencil and a sheet of paper leaves a mark on the paper.
Friction between a bicycle brake pad and the rim of a wheel causes the wheel to stop turning.
Did you ever rub your hands together to warm them up, Why does this make your hands warmer? The answer is friction.
Why Friction Occurs
Friction occurs because no surface is perfectly smooth. Even surfaces that look smooth to the unaided eye make look rough or bumpy when viewed under a microscope. Look at the metal surfaces in the Figure below. The aluminum foil is so smooth that it's shiny. However, when highly magnified, the surface of metal appears to be very bumpy. All those mountains and valleys catch and grab the mountains and valleys of any other surface that contacts the metal. This creates friction.
Factors that Affect Friction
Rougher surfaces have more friction between them than smoother surfaces. That's why we put sand on icy sidewalks and roads. Increasing the area of surfaces that are touching also increases the friction between them. That's why you can't slide as far across ice with shoes as you can on the thin blades of skates. The greater surface area of the soles of the shoes cause more friction and slow you down.
Heavier objects also have more friction. Can you explain why?
Heavier objects press together with greater force, and this causes greater friction between them.
Friction Produces Heat
You know that friction produces heat. That's why rubbing your hands together makes them warmer. But do you know why? Friction causes the molecules on rubbing surfaces to move faster, so they have more energy. This gives them a higher temperature, and they feel warmer. Heat from friction can be useful. It not only warms your hands. It also lets you light a match as shown in the Figure below. On the other hand, heat from friction between moving parts inside a car engine can be a big problem. It can cause the car to overheat.
How is friction reduced between the moving parts inside a car engine?
To reduce friction, oil is added to the engine. The oil coats the surfaces of the moving parts and makes them slippery. They slide over each other more easily, so there is less friction.
Friction is always parallel to the surface in contact.
In some cases, friction is desirable while in other cases, friction reduces the effectiveness of machines. Without friction, you would not be able to walk, the wheels on a vehicle would have no grip on a road surfacing and the vehicle would not be able to move forward.
On the other hand, friction is undesirable in most of the cases. Friction causes mechanical parts to seize and wear out.
Fun with Friction:
Take two pieces of paper. Wad one of the pieces of paper into a ball. Leave the other piece of paper like normal.
Hold the pieces of paper above your head. Drop the pieces at the same time. The wadded piece will fall to the ground immediately. The flat piece of paper will flutter down more slowly because it has more surface area to create friction or drag on the air as it drops.
Explanation:
Imagine a case in which a block is kept on another block and rough surfaces between them. And, the lower block is moved suddenly with a fairly large force. In such a case the upper block would a force supporting motion.
The most basic example of this can also be,
Our walking,.... When we walk the frictional force acting on our body by earth makes us move forward as earth exerts frictional force on us.... The same would certainly not happen if the floor is oily.