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what are contact forces and according to: https://www.physicsclassroom.com/class/newtlaws/Lesson-2/Types-of-Forces

it says there are 6 types of contact forces. I am having doubt with applied force and normal force because both acts when there is contact between two bodies when we push a book kept on a table we take normal force from table surface, but what about the contact between my hand and book we say that applied force, when we push a wall horizontally we say its reaction force is normal force but how ?? when we kick a ball we say we applied a force but where is the normal force between my foot and ball surface which came in contact during kicking, or when we hit a ball by a bat we say we apply a force with bat on the ball but what about normal force between bat and ball surface. when we pull a string attach to a celling we say we applied a force on the string but what about the contact between my hand and string surface where is normal force between them. i am so much confused please somebody help me with this.

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2 Answers 2

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It seems like you are misinterpreting the words 'applied' and 'normal'. You are thinking that applied force is some different type of force from normal force. You are thinking that there is some 'applied' force plus 'normal' force acting at same time between your foot and ball and that's where you are confused.

In reality the 'normal' force is the actual 'applied' force and it is the 'normal' force that is causing the motion of ball. The site you provided seems to be wrong because currently I am unable to remember any type of contact 'applied' force that is different from other mentioned contact forces.

Your foot apply normal force on ball and in return ball apply same amount of normal force on your feet that you feel when kicking. The normal force applied on ball cause an impulse and the ball start moving.Diagram

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  • $\begingroup$ it means every force which i apply on a body all are normal force? $\endgroup$
    – user379089
    Oct 20, 2023 at 10:45
  • $\begingroup$ or combination of normal and friction force?? $\endgroup$
    – user379089
    Oct 20, 2023 at 10:51
  • $\begingroup$ @HarshitRaj No I meant to say that in the site you provided there were many contact forces mentioned and they covered all types of forces that can be applied on body. 'Applied' force is not any different force from other mentioned forces. 'Applied' force means a force that is applied on the body and it could be any force it could be tension or any type of other force also. $\endgroup$ Oct 20, 2023 at 13:41
  • $\begingroup$ it means if i push or pull or lift any block the force i am applying is somewhat combination of normal and friction force ??? $\endgroup$
    – user379089
    Oct 20, 2023 at 15:01
  • $\begingroup$ @HarshitRaj Yes and not only friction and normal but it could also be tension or spring force $\endgroup$ Oct 20, 2023 at 15:07
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With the exception of the frictional force, which only acts parallel to a surface, the component of any of the other listed contact forces perpendicular to a surface is a normal force.

Hope this helps

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