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GenX-Education
  • 7/18/2024
Transcript
00:00hi kids today we will learn about internal and external forces all types
00:10of forces are either external or internal forces external forces any
00:20force that acts on a structure from outside is known as external force for
00:28example wind pushing pulling are external forces as force is being
00:39applied from the outside of the object
00:43internal forces any force that acts from within the structure is called internal
00:51force let's learn it with examples here is a tree which is being blown by wind
00:59but it does not fall down what forces are acting on it there is external force
01:07of wind which is blowing it out and the internal force from the tree is
01:13preventing it from falling down here is another example this girl is trying to
01:22bend the scale but the scale is not breaking down so what forces are acting
01:30on it the girl is applying the muscular force to bend it and there is internal
01:38force in the scale which is preventing from breaking down so internal forces
01:47acts from within the object and external forces acts from outside the objects now
01:54let's learn about some internal forces compression a force that squeezes a
02:03material or try to make the material shorter or smaller here is a sponge if
02:11you press against the sponge you are creating compression inside the sponge
02:17when you release the pressure applied on the sponge the compression forces works
02:23from inside of the sponge and the sponge gets back to its original form here is
02:31spring now compress the spring now when you release a spring the spring will
02:39exert the opposite force and we'll get back to its original shape so when you
02:46compress an object it exerts back force in the opposite direction now let's
02:53learn about another internal force which is tension we learn compression is
03:00created when we try to make an object smaller exactly opposite to it tension
03:09is created in the structure or an object when it is made bigger or longer
03:17examples take a rope or an elastic object now pull it from both sides now
03:25the force that develops inside the rope due to pulling is tension when you
03:33release the pulling force the elastic will come back to its original shape due
03:38to tension one very good application of this tension force is catapult a stone
03:45or anything is placed in the catapult and the elastic strings are stretched as
03:51far possible it produces the tension in elastic strings due to its elongation
03:58and when the elastic string is released the tension force acts and the elastic
04:06comes back to its original shape quickly and the object goes far with speed so
04:12kids remember when you shorten something there develops a force of compression in
04:20it when you elongate something there develops a force of tension in it here
04:29is a simple beam bridge now let's see the types of forces acting on it on the
04:36upper surface of the bridge compression is created due to the live load or the
04:42weight that the bridge is carrying and on the lower surface of the beam bridge
04:48the tension is being created as the lower surface is stretched or elongated
04:54now let's learn another force and it's torsion we learned that compressing an
05:03object creates compression pulling an object from both ends creates tension
05:10now when you twist an object it creates torsion different materials response to
05:17torsion in different ways some may change their shape or some may even break now let's
05:27learn about another type of internal force and it's bending bending an object creates
05:36bending force in the process of bending both compression and tension are created
05:45on an object if you bend a scale or an object the side which is elongated develops tension
05:54and the side which is getting compressed develops compression and this is what happens in the case
06:05of beam bridges due to traffic or live load the upper surface is compressed or shortened
06:13and develops compression and the lower surface is elongated and develops tension so kids today
06:26we learned about internal and external forces now you may go ahead and take a quiz to learn more