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MedAdvance Internship ProgramMedAdvance is an internship program based out of the Scientific Education and Research Institute in Thornton, CO. As a member you may lead and participate in Anatomy/Suture labs and Shadow Doctors. In addition to these opportunities, the Scientific Education and Research Institute is a medical device training facility that has doctors visit from all around the world to learn about new medical technology. This gives interns the opportunity to, not only meet health professionals from around the nation, but also to become familiar with the latest medical technology!!! MedAdvance is having an Open House on Thursday September 29th at 6-8:30pm at the Scientific Education and Research Institute. The address is 9005 Grant st. Thornton, CO 80229. If you have any more questions about the internship or would like to RSVP for the Open House, please feel free to contact hogan.slack@themedadvance.com.Announcements CAPA Set #5 due Friday at 10 pm

This week in Section Assignment #3: Forces, Newtons Laws, Free-Body Diagrams Print out and bring the assignment to your section

Complete reading all of Chapter 4

Step 1: Draw a free-body diagram

Fg = mgNote that Normal Force is always Perpendicular (i.e. normal) to the surface.

In this case, it is not in the opposite direction to the gravitational force.

Fg = mgxyWe could choose our usual axes. However, we know that we will have motion in both the x and y directions.Step 2: Choose a coordinate systemxyIf we pick these rotated axes, we know that the acceleration along y must be zero.Step 3: Write down the equations Fx = m ax , Fy = m ay

Problem: Fg doesnt point in a coordinate direction.Must break it into its x- and y-components.Fg = mg

|F(gravity)| = mgF(gravity)y F(gravity)x Clicker QuestionRoom Frequency BAWhat is the angle a labeled above?a = 90 degreesB) a = qC) a = 90 q D) Cannot be determineda90 q90

Fg = mgStep 3: Write down the equations Fx = m ax , Fy = m ay NFx = mg sin(q)

Fy = N mg cos(q)We also know that ay = 0, there is no motion in that direction.

Fy =may=0= N mg cos(q)Step 4: Solve the Equations

As expected, maximum acceleration if straight down (q=90 degrees), ax = g.

Recall x-y definition

A mass m accelerates down a frictionless inclined plane.

Which statement is true?N < mgN > mgN = mg+x+y-mg cos -0 = Fy = N mg cos N = mg cos < mgClicker QuestionRoom Frequency BA

The driver of a car parked on a hill releases the brake and puts the car in neutral

Let = normal force = force of gravity = acceleration of the car.Which of the following is true?

Clicker QuestionRoom Frequency BA+xFfcmTwo boxes with masses M and m are glued together. Force F is applied to Box 1. Force fc is the contact force that Box 1 exerts on Box 2. Box 1Box 2F = fcF > fcF < fcIndeterminate from information givenClicker QuestionRoom Frequency BAM* Frictionless surfaceMm+xFfcmBox 1Box 2Draw the free-body diagram for each box!MmFfcWhat other forces are acting on either box?Gravitational force down on both boxes, and Normal force up on both boxes.However, since there is no vertical motionwe sometimes do not bother to write them down.What about Newtons Third Law? fcApply Fx = ma. (ignore vertical forces, no vertical motion)MmFfcfcF-fc = MaMfc = mamSince the boxes are fixed (glued) together aM = amaM=(F-fc)/Mam =fc/m =

Assume Box 1 has a mass of 2 kg and Box 2 has a mass of 1 kg. If a force of 1 N is applied to Box 1, what is the contact force between the boxes?

1 N N1/3 N 2 N3 N

M+xFfcmBox 1Box 2

Clicker QuestionRoom Frequency BAAssume a force F is applied to Box 1 at an angle from the horizontal. What will be the equation for the contact force fc?

Mm+xfcmBox 1Box 2

Previous equation:The horizontal component of produces horizontal motion.

F cosF sinClicker QuestionRoom Frequency BA