Announcements • Common Exam 3 is a week from Monday. • Today’s material WILL BE on the exam.
Jan 17, 2016
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?