Keywords & Exercises Class 8 Science Ch- 12 FRICTION

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NCERT Solutions for Class 8 Science Chapter- 12 FRICTION
Complete exercise of Class 8 Science Chapter- 12 FRICTION
Find all q/a questions and answers in a simple way.
00:00 Keywords questions and answers class 8 science chapter 12
00:11 What is ball bearing?
01:41 What is drag?
02:19 What is fluid friction?
03:03 What is friction?
03:48 What is interlocking?
05:01 What are lubricants?
06:13 What is rolling friction?
07:15 What is sliding friction?
08:27 What is static friction?
09:45 Q.-1 class 8 science chapter 12 question 1
12:05 Q.-2 class 8 science chapter 12 question 2
12:44 Q.-3 class 8 science chapter 12 question 3
13:49 Q.-4 class 8 science chapter 12 question 4.
14:48 Q.-5 class 8 science chapter 12 question 5.
16:10 Q.-6 class 8 science chapter 12 question 6.
17:46 Q.-7 class 8 science chapter 12 question 7
19:40 Q.-8 class 8 science chapter 12 question 8
22:23 Q.-9 class 8 science chapter 12 question 9
23:44 Q.-10 class 8 science chapter 12 question 10
keywords
BALL BEARING
DRAG
FLUID FRICTION
FRICTION
INTERLOCKING
LUBRICANTS
ROLLING FRICTION
SLIDING FRICTION
STATIC FRICTION
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) Sprinkling of powder on the carrom board ________ friction.
(e) Sliding friction is ___________ than the static friction.
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
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
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.
5. You spill a bucket of soapy water on a marble floor accidently. Would it
make it easier or more difficult for you to walk on the floor? Why?
6. Explain why sportsmen use shoes with spikes.
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?
8. Explain why sliding friction is less than static friction.
9. Give examples to show that friction is both a friend and a foe.
10. Explain why objects moving in fluids must have special shapes.