# MP Board Class 8th Science Solutions Chapter 12 Friction

## MP Board Class 8th Science Solutions Chapter 12 Friction

### MP Board Class 8th Science Friction NCERT Textbook Exercises

MP Board Class 8 Science Chapter 12 Question 1.
Fill in the blanks:
(a) Friction opposes the …………. between the surfaces in contact with each other.
(b) Fraction depends on the …………… of surfaces.
(c) Friction produces …………….. .
(d) Sprinkling of powder on the carrom board …………. friction.
(e) Sliding friction is ……………. than the static friction.
(a) relative motion
(b) nature
(c) heat
(d) reduces
(e) less.

MP Board Class 8 Science Chapter 9 Friction Question 2.
Four children were asked to arrange forces due to rolling, static and sliding frictions in a decreasing order. Their arrangements are given below. Choose the correct arrangement.
(a) Rolling, static, sliding.
(b) Rolling, sliding, static
(c) Static, sliding, rolling
(d) Sliding, static, rolling.
(c) Static, sliding, rolling

Class 8 Science Chapter 12 MP Board Question 3.
Alida runs her toy car on 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.
(a) Wet marble floor, dry marble floor, newspaper and towel.

Class 8 Science Chapter 12 Question Answer In English Question 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.

The frictional force will act parallel to the inclined surface, opposite to the direction of the sliding of book.

Class 8 Subject Science Chapter Friction Question 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?
It is difficult to walk on a soapy floor because layer of soap makes floor smooth. The coating of soap reduces the friction and the foot cannot make a proper grip on the floor and it starts getting to slip on the floor.

Science Ch 12 Class 8 Question 6.
Explain why sportsmen use shoes with spikes?
Sportsmen use shoes with spikes to increase the friction so that their shoes do not slip while they run or play.

Friction Class 8 Question 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?
Seema will experience more frictional force because the heavy object will be pressed hard against the opposite surface and produces more friction.

Class 8 Science Ch 12 Question 8.
Explain why sliding friction is less than the static friction.
When the box starts sliding, the contact points on the surface of the box do not get enough time to lock into the contact points of the floor. Hence, the sliding friction is slightly less than the static friction. This is why the sliding friction is always less than the static friction.

Class 8 Chapter Friction Question 9.
Give examples to show that friction is both a friend and a foe.
Friction is a friend because:

1. We cannot imagine to be able to walk without friction.
2. We cannot write with pen or pencil in absence of friction.
3. The automobiles could not be started or stopped or turned to change the direction of motion if there were no friction between the tyres of the vehicle and the surface of the road.
4. We cannot fix a nail in the wall or tie a knot if there is no friction.
5. No building could be constructed without friction.

Friction is a foe because:

1. It wears out the materials such as shoes, screws and ball bearings.
2. Friction causes heat. When a machine. is operated, heat generated causes much wastage of energy. Thus, Friction acts as a friend as well as a foe. Also, friction is a necessary evil.

Class 8 Friction Numericals Question 10.
Explain why objects moving in fluids must have special shapes.
When objects move through fluids, they have to overcome the friction acting on them. Efforts are therefore made to minimize the friction so objects are given special shapes. Idea of such shapes come from the body structure of birds and fishes which have to move about in fluids all the time. Such shapes are called streamlined. Giving such shapes to the ships, planes and cars is called streamlining.

### MP Board Class 8th Science Friction NCERT Extended Learning – Activities and Projects

Question 1.
What role does friction play in the sport of your choice? Collect some pictures of that sport in action where friction is either supporting it or opposing it. Display these pictures with proper captions on the bulletin board of your classroom.
Do yourself.

Numericals On Friction Class 8 Question 2.
Imagine that friction suddenly vanishes. How would the life be affected. List ten such situations.
Do yourself.

Lesson 12 Science Class 8 Question 3.
Visit a shop which sells sports shoes. Observe the soles of shoes meant for various sports. Describe your observations.
Do yourself.

Class 8th Friction Question 4.
A toy to play with:
Take an empty matchbox. Take out its tray. Cut a used refill of a ball pen of the same width as the tray as shown in the figure below. Fix the refill with two pins on the top of the tray as shown in Fig. 12.2. Make two holes on the opposite sides of the tray. Make sure that the holes are large enough to allow a thread to pass through them easily. Take a thread about a metre long and pass it through the holes as shown. Fix beads at the two ends of the thread so that it does not come out. Insert the tray in the outer cover of the matchbox. Suspend the match box by the thread. Leave the thread loose. The match box will start falling down due to gravity. Tighten the thread now and observe what happens. Explain your observation. Can you relate it to friction?

Do yourself.

### MP Board Class 8th Science Friction NCERT Additional Important Questions

Class 8 Ch Friction Science Question l.
What is friction?
The force acting equal and opposite surfaces? Does it depend on the smoothness to the relative motion of two objects in of the surface?
contact is known as friction.

Friction Class 8 Extra Questions Question 2.
How is friction caused? the surfaces. Yes, it depends on the
Friction is caused by the irregularities smoothness of the surface. It is the least on the two surfaces in contact. the smoothest surface.

Class 8 Science Chapter 9 Friction Question Answer Question 3.
In which direction does friction work? Smooth surfaces provide less friction, whereas
Frictions works opposite to the motion, rough surfaces provide more friction.

Science Class 8 Chapter 12 Question Answer Question 4.
Is the friction the same for all the
No, friction is not the same for all

Class 8 Friction Question Answer Question 5.
Why does the friction between two
Since the friction is due to the interlocking of irregularities in the two surfaces which slide with respect to each other, it is obvious that the force of friction will increase if the two surfaces are pressed harder. One can experience it by dragging a mat when nobody is sitting on it and when a person is sitting on it.

Class 8 Friction Chapter Question 6.
What would happen if there were no force of friction? Imagine and describe in your own words.