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Natural sciences

Energy transfers and forces

A. forces

Educator section


Fig 1 - A force can change the course (direction) of a moving object.

Fig 2 - A force can halt a moving object.

Fig 3 - A force change the shape of an object.

Fig 4 - A force can change the speed of a moving object.

Fig 5 - A force can make an object rotate.

Leaner section


1. Contact forces

The vehicle in the illustration has broken down and cannot move by itself. The tow truck has to pull it.

This car also cannot move by itself. The man has to push it.

When something has to be pulled or pushed, we say that we must exert force on it. You use the force of thrust to push something away from you, or the force of attraction to pull something towards you.

Examine the following illustrations and indicate whether they show forces of thrust or of attraction.

We cannot see force, but we know that it is there because we observe its effect. The above illustrations show that force can move a stationary object.

Activity: to identify the effect of forces [lo 1.3]

The following illustrations show more of the effect of forces. Are you able to identify them?

Fig. 1: The tennis player hits the ball away from her.

Fig. 2: The driver uses the brakes to stop the car.

Fig. 3 The force of attraction is exerted on the elastic band.

Fig. 4: The force of thrust in the same direction as the motion is exerted on the rolling ball.

Fig. 5: The athlete swings the hammer to rotate it around him

Note down your deductions:

Fig 1: _______________________________________________________________




Fig 2: _______________________________________________________________




Fig 3: _______________________________________________________________




Fig 4: _______________________________________________________________




Fig 5: _______________________________________________________________




Sometimes the effect of force is not visible. When you push against a wall, you are using force, but the effect cannot be seen. But when there is an egg between your hand and the wall, you will be able to observe that you have exerted force quite plainly!

2. Forces that operate over distance:

It is even possible to bring objects into motion or to change the direction of the motion without any contact. Forces that affect objects without making contact are identified as forces that operate over distance.

Three kinds of force can have an effect without any contact with objects:

  • Magnetic force
  • Electrostatic force
  • Gravitational force


Learning Outcome 1: The learner will be able to act confidently on curiosity about natural phenomena, and to investigate relationships and solve problems in scientific, technological and environmental contexts.

Assessment Standard 1.3: We know this when the learner evaluates data and communicates findings: generalises in terms of relevant aspects and describes how the data support the generalisation.

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
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
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Natural sciences grade 7. OpenStax CNX. Sep 16, 2009 Download for free at http://cnx.org/content/col11077/1.1
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