7. Which of the following method increases friction? (a) Grooving (b) Streamlining (c) Lubricating (d) Using rollers
8. Which of the following is not a type of friction? (a) Static friction (b) Sliding friction (c) Rolling friction (d) Surface friction
9. Which of the following is correct about rolling friction?
(a) Rolling friction is more than sliding friction. (b) Rolling friction is less than sliding friction.
(c) Rolling friction is more than static friction.
(d) Rolling friction is equal to sliding friction.
Answers
Answer:
7. grooving
8. sliding Friction
9. Rolling Friction is less than the sliding Friction
Answer:
option B must be the answer
because all except B are done/used to reduce friction
Static Friction - the maximum force exerted by a surface on a body so long as it remains stationary is called the force of static friction.
Sliding friction - the minimum force required to keep the body moving over a surface such that it moves equal distances in equal intervals of time.
Rolling friction - the minimum force required to roll a body on a surface.
so A is correct
Rolling friction is the resistance to motion experienced by a body when it rolls upon another. It is much less than sliding friction for same pair of bodies. When one body rolls upon another, there is theoretically no sliding or slip between them. And if both are perfectly rigid, there is no surface of contact.
so B is correct
Explanation:
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