Contact Forces
טקסט Storyboard
- שקופית: 1
- Force PressureA push or a pull on an object is called force. Force changes the speed, state, dimension and direction of an object.
- Ha, this is easy. A force changes the object's speed, direction, state or dimension.
- An example would be when we pull a curtain and push a trolley.
- שקופית: 2
- When the resultant force acting on the body is 0 then it is known as unbalanced force.
- Balanced forces are equal in size and opposite in direction
- they are 2 forces , balanced and unbalanced.
- Kids, I am able to stand because the gravity is pulling me towards the ground, So, it can be also called GRAVITATIONAL FORCE.
- שקופית: 3
- YES MA'AM
- See, now the books fell down. So, there is no physical contact between the books and my hand, It is called NON - CONTACT FORCE.
- See, as I am holding the books, there is a physical contact between the books and my hand, so it is called CONTACT FORCE.
- שקופית: 4
- YES MA'AM
- when a force acts over a large area of an object, it produces small pressure. But, if the same force acts over a small area of the object, it produce a large presssure.
- שקופית: 5
- Ma'am, I tripped over the books. Ooouuch !! It hurts..
- Laura, do you feel your hair being pulled by the computer Screen ?
- Yes Ma'am, I do
- It is because of ELECTROSTATIC FORCE. Before you came into the room, I was watching computer. So, the computer is the Charged Body and your hair is Uncharged. Hence, it was attracting your hair.
- שקופית: 6
- MECHANICAL FORCE, the force exerted by machines.Eg - Engine of a Car, Closing and Opening of Door
- MAGNETIC FORCE, the force exerted by a Magnet or Magnetic substances.Eg - Magnet attracts Iron,
- Ma'am pressure = force --------area
- שקופית: 0
- There are two more forces left. We have done it in class 7. Tell me what it is.
- It's ok, Darling. It happened because of FRICTIONAL FORCE. It is the force that opposes motion when two or more objects are in contact move in respect to each other.
- Notice this students. For holding the books, my muscles are being used too. So, it can be also called MUSCULAR FORCE.
- Correct both of you!
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