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

Friction (Assignment)

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.