Deformaciones de los cuerpos_ingl.ppt

8/10/2019 Deformaciones de los cuerpos_ingl.ppt

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UNIT

9

Natural Science. Secondary Education, Year 2

Forces and their effects

EQUILIBRIUM

influence the bodies’

MOVEMENT OR STATE OF REST SHAPE

cause changes in their

depending on the

NATURE OF THE BODY INTENSITY OF THE FORCE

RIGID HARD)LASTIC MALLEABLE)

When forces act on bodies, they

cause changes in their

bodies are classified as

ELASTIC

if, once the force stops, if, once the force stops, if, once the force stops,

THERE IS NO NOTICEABLE CHANGEHEY REMAIN DEFORMEDHEY RECOVER THEIR ORIGINAL SHAPE

ACTIVITIES



UNIT

9



A spring is an example of anelastic body. Rubber bandsand balloons are otherexamples. However, there areno perfectly elastic bodies.For example, if you pull veryhard on a spring you’ll changeits shape permanently, and it

will no longer behave like anelastic material.When this happens, we saythat the spring’s elastic limithas been exceeded this isshown in the photo). The bodywill now behave like amalleable material.



UNIT

9



Malleable materials remain deformed after a force has been applied. Plasticine is anexample of a malleable material.Just as there are no perfectly elastic bodies, there are no perfectly malleable bodies.If we apply a strong enough force, they break. This is a characteristic shared by allbodies, and the maximum force we can apply without breaking them is called thebreaking limit.



UNIT

9



We cannot observedeformations in rigid,or hard, materials,like the rocks shownin the photo on theright.However, thesebodies also have abreaking point: all we

have to do is apply astrong enough force.Some bodies, likeglass, have a very lowbreaking point. Theycan be broken usinga weak force. We callthese fragile materials.



UNIT

9


Forces and their effectsCars used to be made of hard materials, but now they are now made of moremalleable materials, and engineers perform careful analyses on the deformationsthat would occur in the hard components of the car in the case of an accident in

order to prevent passengers from being injured:a) Why do you think this is?

b) How do you think the human body behaves when small forces are applied to it?And when it is hit very hard?

1.



UNIT

9



What type of body does aspring become when its elasticlimit is exceeded?

• Elastic.

• Plastic.

• Rigid.

2.

Classify the bodies on the rightas elastic, plastic and rigid,considering how or whetherthey change shape when aforce is applied to them.

3.



UNIT

9


Forces and their effectsAnalyse the behaviour of the trees in the photo according to how or whether theychange shape when a force is applied to them.

4.

Deformaciones de los cuerpos_ingl.ppt

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