Phys 201 1nd Edition Lecture 6 Outline of Last Lecture I. Solving for projectile motion and range equations.Outline of Current Lecture II. ForcesIII. Newton’s LawsA. 1st LawB. 2nd LawIV. Types of ForcesA. Contact forcesB. Action at a DistanceV. Free Body DiagramVI. Separating x and yCurrent LectureForce:All movement happens because of acceleration. Acceleration happens because of force. Forces are vectors, meaning they have a magnitude and direction, just like acceleration. We can have one or many forces acting on an object at once. When we have multiple forces acting on an object at the same time, we can add these forces together (just as we would add any other vectors together) and the result is referred to as a “Net Force”. When we can see acceleration of an object, we know we have a Net force.Newton’s Laws of Motion:Law 1: “An object at rest will remain at rest and an object in motion will remain in motion until it is acted upon by another force”. This law can also be interpreted as “An object has a constant velocity unless a Net force acts on it”.Law 2: “Net force is equal to product of the mass and the acceleration of an object”. This law is merely an equation; ∑Fnet=ma where ∑F=the sum of the forces acting on an object, a=acceleration, and m=mass.Net force is measured in kg(m)/s2, which is simplified to Newtons (N).Example:These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.You are pushing wagon across a flat surface. You are pushing on the wagon’s handle, which is at a 40◦ angle, with a downward force of 500N. What is the horizontal force of the wagon?We can solve this equation just like we would solve any vector equation. Essentially, our downward forceof 500N is the magnitude of the hypotenuse of a triangle, and we are looking for the magnitude of the x component. This means we will use trigonometry to solve for Fx. Cos(θ)=Fx/F Fx=Cos(40)(500)=383NIt’s important to remember that even though we are pushing with a downward force, the wagon will only move horizontal, not in the direction that we are pushing. This is because of the net forces acting onthe wagon. Even though we don’t directly see them, gravity and the ground are both simultaneously applying force to the wagon.Different Kinds of forcesSimple Forces: Contact forces: As the name implies, contact forces come from two forces touching one another. There are two types of contact forces; normal and tension. Normal force refers to the force pointing up. If you set a book on a desk, the book stays in place because the desk is applying normal force to the book. Tension force works like a push or pull mechanism. If I’m playing with a ball on the end of a string, when Idrop that ball the string will tighten and the ball will spring back up, due to tension force.Action at a Distance force:These forces do not require any kind of contact. The main force we think about when we talk about action at a distance forces is gravity. The equation for calculating the force of gravity is Fg=m(g). Free body diagram:The best way to represent net forces acting on an object is to use a free body diagram. These diagrams typically use a box to represent an object, and arrows to represent the different forces the object is exerting. If we think back to our wagon example, our free body diagram would look something like this;WeightFThe force of weight of an object will always be applied downwards. This is because weight is dependent on gravity, which is another force that is always applied downward. The equation for determining weight is Weight=m(g)Example: What force is necessary to accelerate a 50g cannon ball to 40m/s in .05s?F=ma, so we first need to find the acceleration. a=ΔV/Δt  a=40/.05=800m/s2Because Newtons are measure in kg(m)/s2, we need to convert our mass of 50g to kg. This makes our mass .05kg. F=(.05kg)(800m/s2)=40NLike everything with vectors, forces can be divided into x and y forces. However, certain forces can only be one or the other because they are very directionally specific. The only force in the x direction is, literally, x force or Fx. Normal force, gravity, and y force (Fy) are all forces that affect the y direction of an object. Knowing this, we can separate our force equation into Fx=max and Fy=may.Example:A force of 9N is applied to a block on a horizontal surface at a 30◦ angle. The ball has a horizontal acceleration of 5m/s2. What is the mass of the block and what is the normal force of the surface?Since we know that ax=5 we can calculate force using trigonometry again. F=ax/Cos(θ)  F=5/Cos(30)=7.8NWe plug this value for force into the equation F=ma  7.8=m5  m=7.8/5=1.56kgTo find the normal force we need to expand the equation. Because ∑Fy=may and ∑Fy=Fy + Normal(n) + weight(mg), we should expand our equation out to Fy+n+mg=may. In this case, we know mass=1.56kg, meaning weight=(1.56)(9.81)=15.3, Fy=9N and ay=0. Since we’re solving for n we can rewrite the equation as n=may+ Fy+ mg n=0+