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00:00Hi kids! Today we will learn different types of forces. So let's get started.
00:09In learnt, force is either pushing or pulling of an object.
00:14And there are many types of forces, depending on whether the force is resulting from the contact between two objects or there is no contact between two objects.
00:28Contact force is a force in which an object comes in contact with another object.
00:35Contact forces are also direct forces.
00:39Examples, pushing a car, pulling a rope, opening a door, closing a door, kicking a ball, running a bicycle.
00:48In all these actions, forces apply and two objects come in contact with each other.
00:55Examples of contact forces are friction, normal force or applied force, buoyancy, muscular, wind, moving water, non-contact forces, non-contact forces.
01:13Here, objects move without coming in contact with another object.
01:18They are also known as invisible forces.
01:22Examples, gravity, magnetic force, electrostatic force.
01:29Now let's learn each type of force one by one.
01:34First is applied force.
01:37Applied force is that force which is applied to an object by a person or another object.
01:47If a person is pushing or pulling an object, let's say a chair, then there is an applied force acting upon the chair.
01:56So applied force is a contact force as it can move the object only if it is in contact with the object.
02:06Now let's see what is a magnetic force.
02:10Magnetic force.
02:12A magnet is an object that can push or pull materials made of iron, steel or nickel.
02:18A magnet is made of these same materials.
02:23Here are some pins, keys or any small things that are made of iron or steel.
02:29Now bring a magnet closer to these things.
02:32What do you see?
02:34All things will get stuck to the magnet.
02:37It is because the magnet attracts or pulls all these things made of iron, steel or nickel.
02:45The magnet pulled these things without coming in contact with these things.
02:50So there was an invisible force that pulled these things towards the magnet.
02:56So this is non-contact force.
03:00We all love to stick stickers of our choice to our refrigerator.
03:05Why do they get stuck to the refrigerator?
03:09It is because a small magnet is attached at their back and the refrigerator is made up of iron.
03:17As we bring them closer to the door of the refrigerator, they get attached to it
03:23due to the pulling effect between a magnet and a refrigerator.
03:29So this is a non-contact force.
03:34Now here is another non-contact force.
03:37It is gravity.
03:40It does not require to come in contact with the object to move it.
03:45Now let's see what is force of gravity.
03:49You have a pencil and you just dropped it.
03:53Why does it fall to the ground?
03:56Why doesn't it stay in the air or goes up?
03:59Do you ever think?
04:01It is because of the pulling force of the ground.
04:05This pulling force of the ground is called gravity which attracts everything towards it.
04:12So it's a non-contact force.
04:15All objects on earth experience a force of gravity
04:20that is directed downwards towards the center of the earth.
04:25Now let's learn about another non-contact force which is called friction.
04:31And let's see if it's a contact force or a non-contact force.
04:37Friction is a force that resists motion.
04:40When two things are in contact, it too occurs when two things rub together.
04:46Friction can cause problems but it also helps us in many ways.
04:53Here is a toy car.
04:55First, push it on a rough surface and record how far it goes.
05:01Now, push the same car with the same force on a smooth surface.
05:06Again, record how far it goes.
05:10What are the results?
05:12The car went much further on a smoother surface.
05:17It is because the rough surface poses greater friction
05:22or opposing force for any movement.
05:26And the smooth surface poses lesser friction
05:29or lesser opposing force for any movement.
05:34So, friction is a force that acts against every motion
05:38and it works in the opposite direction of the force causing the movement.
05:44It is because of the friction that object slows down and eventually stops.
05:50So kids, today we learned more about forces.
05:55Now you may go ahead and take a quiz to learn more.
05:59Bye-bye.