Monday, 3 July 2017

CBSE Class 8 - Science - Friction (Assignment) (#cbseNotes)

Friction (Assignment)

CBSE Class 8 - Science - Friction (Assignment) (#cbseNotes)

Q1: Name the following:

 Type of surfaces that produces minimum friction _____________

 Type of surfaces that produce maximum friction  _____________

 A shape that reduces drag _____________

Friction with minimum magnetic magnitude _____________

 Friction with maximum magnitude _____________

 Two types of fluids _____________



 Frictional force exerted by fluids _____________

 A device that converts sliding friction
into rolling friction _____________

 A self-adjusting force which opposes the
relative motion of two surfaces _____________

 Graphite powder, grease, oils are examples of   _____________


Q2: Fill in the blanks

Force always opposes the motion ________________.

Is a device used to measure force acting on an object _______________.

Ball bearing is commonly used in bicycle wheels to _________ friction.

Gymnasts apply of course substance on their hands to ________ friction.

Frictional force is an example of ____________ force.

Limiting friction is ___________ of the area of contact.

Force of static friction is ___________ ___________.


Q3: Complete the table given below



Advantages of friction Disadvantages of friction
1. Help us write Leads to wastage of energy
2.
3.
4.
5.
6.


Answers:
Q1:
smooth/polished surface
rough surface
streamlined shape
rolling friction
static friction
liquids and gases
fluid friction or drag
ball bearing/ wheel
friction
lubricants

Q2:
friction
spring balance
reduce/decrease
increase
contact
independent
self adjusting

Q3:


Advantages of friction Disadvantages of friction
1. Help us write Leads to wastage of energy
2. Help us wal Friction produces heat which reduces the efficiency of machines.
3. Allows vehicles to move on the road. leads to wear and tear of machine parts
4. Enables us light a matchstick Drag slows down the speed of the object.
5. Can write on blackboard with a checque. Soles of shoes wear down due to friction.
6. Enables us write down on a page using pen or pencil. Due to friction, engines of automobiles consume more fuel, hence increases costs.



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