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Natural sciences

Grade 9

Energy, forces and machines

Module 19

Forces and friction

Activity:

Describing and applying the terms force and friction

[lo 1.2; lo 1.3; lo 2.3; lo 2.4]

The sketch that follows represents a brick lying on a table in front of you. Discuss ways in which the brick could be made to move and decide on one method. In science we indicate forces and the direction in which they operate by means of an arrow.

Indicate the possible directions of motion by means of arrows.

  • How would you define a force?
  • You could have applied tractive power (pull) or thrust power. When you stop pulling or pushing the brick, it stops moving or comes to rest. Why? Another simultaneous force that opposed the force that you were applying must have been in operation. This force is known as FRICTION .

List examples of friction from common daily experiences.

Assessment

Were you able to describe the term “force”, indicate the lines of action on the sketch and provide examples of friction?

[LO 2.4]

Investigation: FORCES AND FRICTION

Use a stopwatch, a spring balance, a brick, a smooth piece of cardboard or perspex as big as the base of the brick, a length of string, some baby-powder and a skateboard.

  • Tie the brick to the spring balance, using the length of string.
  • Move the spring balance along slowly to bring the brick into motion, checking the balance to note the position of the needle when the brick begins to move.
  • Pull the brick over a distance of 5 metres – get someone to time this action and enter the information on a table.
  • Repeat this procedure, but secure the brick to the cardboard or perspex. Time the action and tabulate the details. Try to apply sufficient force for the needle to give the same reading as previously. Use same distance stretch for every procedure.
  • Repeat the procedure, but secure the brick to the skateboard.
  • Do three repeats of all of the above. Use baby powder as an alternative in all three and sprinkle on wheels of skateboard.

1. Why was it necessary to repeat the experiment three times?

2. Why did you get different time readings for the action when you pulled the brick only, the brick on cardboard or perspex and the brick on the skateboard?

3. Mention other methods by which friction can be reduced.

4. Think about a motor vehicle and list five examples to show that it is necessary to use a lubricant or some other method designed to reduce friction. Explain each example.

[LO 1.2; LO 1.3; LO 2.3]

Remember the following:

  • Forces can:
  • change the shape of an object;
  • increase or slow down the speed of an object;
  • redirect the motion of an object and
  • rotate an object around a fixed point.
  • There are forces of attraction or pull (tractive forces) and of thrust (push) and can both operate directly or over a distance.
  • Most forces, however, only come into operation when objects are in contact with one another.

Questions:

1. Provide an example of each of the following effects:

  • change of form
  • change of speed
  • forces that operate when there is no contact
  • forces of thrust

Activity:

Researching a scientist who made an important contribution to science: Isaac Newton

Questions & Answers

what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
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Source:  OpenStax, Natural sciences grade 9. OpenStax CNX. Sep 15, 2009 Download for free at http://cnx.org/content/col11069/1.1
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