Premium Online Home Tutors

3 Tutor System

Starting just at 265/hour

(a) rolling, static, sliding

(b) rolling, sliding, static

(c) static, sliding, rolling

(d) sliding, static, rolling

Answer :

Four children were asked to arrange forces due to rolling, static and sliding frictions in a decreasing order. Their arrangements will be as follows:-

**(c) static, sliding, rolling.**

**EXPLANATION**

In rolling friction, two surfaces never comes in contact for even a little time period as the object gets rolled and continuously changes its surface of contact within a span of seconds. So in rolling friction, the time given for interlocking is almost negligible, and thus there is no interlocking at any point of the time, as a result of which rolling provides very less friction as compared to sliding friction and static friction.

While in case of sliding friction, the time given for interlocking is small as compared to that of static friction but as interlocking takes place for some moments, so the resulting interlocking is not so strong. With the application of less external force, one can overcome this type interlocking. Hence sliding provides less friction as compared to static friction.

In case of static friction, the interlocking between the two surfaces of the two objects is much more stronger than the interlocking provided by the sliding friction. So this type of interlocking requires more external force to overcome the friction created because of this interlocking.

- Q.1 Fill in the blanks. (a) Friction opposes the ______ between the surfaces in contact with each other. (b) Friction depends on the ______ of surfaces. (c) Friction produces ______ (d) The sprinkling of powder on the carrom board _______ friction. (e) Sliding friction is _______ than the static friction.
- Q.3 Alida runs her toy car on a dry marble floor, wet marble floor, newspaper and towel spread on the floor. The force of friction acting on the car on different surfaces in increasing order will be (a) wet marble floor, dry marble floor, newspaper and towel. (b) newspaper, towel, dry marble floor, wet marble floor. (c) towel, newspaper, dry marble floor, wet marble floor. (d) wet marble floor, dry marble floor, towel, newspaper.
- Q.4 Suppose your writing desk is tilted a little. A book kept on it starts sliding down. Show the direction of frictional force acting on it.
- Q.5 You spill a bucket of soapy water on a marble floor accidentally. Would it make it easier or more difficult for you to walk on the floor? Why?
- Q.6 Explain why sportsmen use shoes with spikes.
- Q.7 Iqbal has to push a lighter box and Seema has to push a similar heavier box on the same floor. Who will have to apply a larger force and why?
- Q.8 Explain why sliding friction is less than static friction.
- Q.9 Give examples to show that friction is both a friend and a foe.
- Q.10 Explain why objects moving in fluids must have special shapes.

- NCERT solutions for class 8 maths chapter 1 Factorisation and Mensuration
- NCERT solutions for class 8 maths chapter 1 Rational Numbers
- NCERT solutions for class 8 maths chapter 1 Factorization
- NCERT solutions for class 8 maths chapter 2 Linear Equations in One Variable
- NCERT solutions for class 8 maths chapter 3 Understanding Quadrilaterals
- NCERT solutions for class 8 maths chapter 4 Practical Geometry
- NCERT solutions for class 8 maths chapter 5 Data Handling
- NCERT solutions for class 8 maths chapter 6 Squares and Square Roots
- NCERT solutions for class 8 maths chapter 7 Cube and Cube Roots
- NCERT solutions for class 8 maths chapter 8 Comparing Quantities
- NCERT solutions for class 8 maths chapter 9 Algebraic Expressions and Identities
- NCERT solutions for class 8 maths chapter 10 Visualising Solid Shapes
- NCERT solutions for class 8 maths chapter 11 Mensuration
- NCERT solutions for class 8 maths chapter 12 Exponents and Powers
- NCERT solutions for class 8 maths chapter 13 Direct and Inverse Proportions
- NCERT solutions for class 8 maths chapter 14 Factorization
- NCERT solutions for class 8 maths chapter 15 Introduction to Graphs
- NCERT solutions for class 8 maths chapter 16 Playing with Numbers

- NCERT solutions for class 8 science chapter 1 Crop Production & Management
- NCERT solutions for class 8 science chapter 2 Microorganisms: Friend and Foe
- NCERT solutions for class 8 science chapter 3 Synthetic Fibers and Plastics
- NCERT solutions for class 8 science chapter 4 Materials: Metals and Nonmetals
- NCERT solutions for class 8 science chapter 5 Coal and Petroleum
- NCERT solutions for class 8 science chapter 6 Combustion and Flame
- NCERT solutions for class 8 science chapter 7 Conservation of Plants and Animals
- NCERT solutions for class 8 science chapter 8 Cell-Structure and Function
- NCERT solutions for class 8 science chapter 9 Reproduction in Animals
- NCERT solutions for class 8 science chapter 10 Reaching the Age of Adolsence
- NCERT solutions for class 8 science chapter 11 Force and Pressure
- NCERT solutions for class 8 science chapter 12 Friction
- NCERT solutions for class 8 science chapter 13 sound
- NCERT solutions for class 8 science chapter 14 Chemical Effects of Electric Current
- NCERT solutions for class 8 science chapter 15 Some Natural Phenomena
- NCERT solutions for class 8 science chapter 16 Light
- NCERT solutions for class 8 science chapter 17 Stars and the Solar System
- NCERT solutions for class 8 science chapter 18 Pollution of Air and Water