Page 138 - SCERT Kerala State Syllabus 8th Standard Basic Science Textbooks English Medium Part 1_Neat

When a body rolls over the surface of another body, the force of friction
which originates is rolling friction. When a body slides on the surface
of another body the force of friction which originates is sliding friction.
Rolling friction is less than sliding friction.

Wheels are used in vehicles to reduce friction. Identify situations
where there is a reduction of friction as a result of rolling and write
them down in your science diary.
Friction is used in many situations in our daily life. Nevertheless
friction has some disadvantages too. Given below are some
situations where friction is beneficial and non beneficial. Tabulate
them.
striking a match stick on the side of a match box.

wear and tear of machines.
ability to hold objects

walking
treading of tyres of vehicles
See "gharshanam
wearing out of tyres prayojanappeduthunnu"
in School Resources in
fuel loss
IT @ School Edubuntu.
Situations where friction is Situations where friction is non
beneficial beneficial

Table 10.5
Find more situations and expand Table 10.5

You might have understood that there are advantages and
disadvantages of friction. What are the different methods to reduce
friction? Let's examine.
Observe the pictures given below.

Fig. 10.8 (a) Fig. 10.8 (b) Fig. 10.8 (c)
Basic Science VIII 137