Announcements

• Common Exam 3 is a week from Monday.• Today’s material WILL BE on the exam.

2

Please indicate your preferred time for an OPTIONAL review session:

A)Weds 2:30-4pmB)Thurs 2:30-4pmC)Friday 11:30-1pmD)Friday 2:30-4pm

Iclicker Question #1

Who performs the theme song for “The Big Bang Theory”

A) Justin BieberB) Barenaked LadiesC) The RescuesD) The SolidsE) Numeriklab

Iclicker Question #1

Who performs the theme song for “The Big Bang Theory”

A) Justin Bieber – Karate Kid theme songB) Barenaked LadiesC) The Rescues – Modern FamilyD) The Solids – How I Met Your MotherE) Numeriklab - NCIS

Iclicker Question #1

After viewing the above highly scientific demonstration, which of the following statements is false?

A) The log is initially in static equilibriumB) After the Roadrunner gets to the end of the log, the net torque on

the log is zero.C) After Wiley E. Coyote sticks his head out of the log, the log is no

longer in static equilibriumD) As the Roadrunner or Coyote move inside of the log, the center of

mass of the log/wildlife system moves.E) The Roadrunner is heavier than the Coyote

http://www.lghs.net/ourpages/users/dburns/RRPhysics/Road_Runner_Physics/Movie_files/LogTunnel.mov

Static Equilibrium – The cliff notes

0F ma

0I

For a rigid body, no net force and no net torque

For all of you mechanical engineers out there, you spend ENTIRE COURSES on this – (a)To make it more difficult, engineers allow the ‘rigid’ objects to deform… bending, twisting, stretching.(b)The hidden truth…. “it’s really physics….”

Iclicker Question #2

Which statement is true regarding the two forces acting on the object below?

A) The object is in force equilibrium but not torque equilibrium

B) The object is in force equilibrium AND torque equilibrium

C) The object is in NEITHER force equilibrium NOR torque equilibrium.

D) The object is NOT in force equilibrium but it IS in torque equilibrium

E) I don’t know which hand to use for the “Right Hand Rule”

Wine Bottle Demo

Leaning Ladder

Iclicker Question #3

For the pole vaulter below, which of the following sets of equation are correct if you use point B as the pivot point for the torque calculation?

A) D+mg=U , 0.75*D+1.5*mg=0B) D+mg=U , 0.75*D-1.5*mg=0C) D+mg+U=0 , 0.75*D-1.5*mg=0D) D+mg=U , (0.75+1.5)*D-1.5*U=0E) D-mg=U , 0.75*D+1.5*mg=0

Balancing Art

Iclicker Question #4

In which direction do you expect the total force of interaction between the rod and wall to be?

A) Only horizontally to the rightB) Only vertically upwardC) There is no force of the wall on the rodD) Horizontally to the leftE) There is a horizontal AND a vertical component to the force

What mass is needed to counter balance the truck?