Rolling Friction
Rolling Friction
When an object (like a wheel) rolls over the surface of another object, the resistance to its motion is called rolling friction. It is always easier to 'roll' than to slide' an object over another object. So, rolling friction is much less than sliding friction. Thus, rolling reduces friction. We will now describe an activity to demonstrate that it is much easier to roll an object over another object than to slide it. It will also show that rolling friction is much smaller than sliding friction.
Let us keep a thick book on a table. Now push the book with your hand [see Figure 11(a)]. We will find that it is not very easy to push the thick book lying on the table and make it move (or slide). We have to apply fairly large amount of force to make the book move (or slide) on the table. This is because when the book lying directly on the surface of table moves, then sliding friction comes into play. The large sliding friction between the surface of table and bottom of thick book makes the book comparatively difficult to move. Now, take three round pencils (round pencils are cylindrical in shape and act as rollers). Place the round pencils parallel to one another on the table top. Let us place the same thick book the round pencils [as shown in Figure 11 (b)]. Now push the book with your hand. When we push the book, the round pencils kept below it start rolling or turning (like wheels) and make the book move forward easily [see Figure 11(b)]. We have a very small amount of force to make the book move when it is placed on rollers round pencils). Thus, it is much more easy to move the book placed on rollers than to slide it directly over the surface of table. It is much easier to move an object kept on rollers than to slide it because rolling friction is much less than sliding friction.
From the above discussion we conclude that when an object rolls over another object, then rolling friction comes into play between them. Rolling friction is much smaller than sliding friction. Since rolling friction is much less (than sliding friction) it is very easy and convenient to pull heavy luggage (like heavy suitcases, etc.) fitted with rollers. Heavy machines can be easily moved from one place to another by placing round logs of wood under them and then pushing with the force of hands. The round logs of wood act as rollers (a kind of wheels) and make it much easier to move the heavy machine kept on them. Figure 12 shows a large block of stone being moved by the use of rollers. Please note that the rollers turn around like the wheels and take the block of stone forward. Thus, rollers are a kind of wheels. We can now understand why wheel is said to be one of the greatest inventions of mankind. This is because wheels greatly reduce friction (by rolling) and hence can be used to move even heavy objects (like cars, buses, trucks and trains, etc.) rather easily.What do you think the rollers do in skating shoes? | |||
| Right Option : A | |||
| View Explanation |
Which of the following Friction occur due to deformation of surfaces ? | |||
| Right Option : A | |||
| View Explanation | |||
It is easier to pull a lawn roller than to push it because pulling _________________ | |||
| Right Option : B | |||
| View Explanation | |||
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Barkha Arora
10thAbhyas institute is one of the best coaching institute in the vicinity of Ambala Cantt area. The teachers of the institute are well experienced and very helpful in solving the problems of the students.The good thing of the institute is that it is providing extra classes for the students who are w...
Aman Kumar Shrivastava
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Anika Saxena
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8thIn terms of methodology I want to say that institute provides expert guidence and results oriented monitering supplements by requsite study material along with regular tests which help the students to improve their education skills.The techniques of providing education helps the students to asses...
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Yatharthi Sharma
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Aman Kumar Shrivastava
10thThird consective year,my ward is in Abhyas with nice experience of admin and transport support.Educational standard of the institute recumbent at satisfactory level. One thing would live to bring in notice that last year study books was distributed after half of the session was over,though study ...
Ayan Ghosh
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