Announcements

Announcements

• CAPA Assignment #12 due this Friday at 10 pm

• Section: Lab #5, Springs and Things (note no prelab)

• Nagle’s office hours 2-3 pm cancelled

• Exam #3 on Tuesday, November 8th at 7:30 pm

• Today is a review of some exam topics….

Tomorrow evening at 7:30 PM:

• Bring a #2 pencil, an eraser, and a calculator.• No outside materials

• No cell phones or smart phones as calculator

• Same room assignments as previous exams

Reminder of Materials Available

• Textbook and example problems in the text

• Professor Dubson’s Chapter Notes (see link on web page)

• Clicker questions as posted in lecture notes

• CAPA problems, solutions on CULearn

• Practice exam and solutions on CULearn

• Lab manuals and problems

PE = work done to move into current configuration

ki

vr

2T

2 f

f rpm60

ar v2

rr 2

0 t

0 t 12t 2

2 02 2

centripetal acceleration

kinematical equations

Clicker Question Room Frequency BA

A projectile is fired straight up and then comes back down to the ground. There is a force of air resistance.

During the entire flight, the total work done by the force of gravity is:A) ZeroB) PositiveC) Negative

During the entire flight, the total work done by the force of air resistance is:A) ZeroB) PositiveC) Negative

Clicker Question Room Frequency BA

A pendulum is launched in two different ways. During both launches, the bob is given an initial speed 3 m/s and the same initial angle from vertical.

Which launch will cause the pendulum to swing the largest angle from the equilibrium position to the left side? A) Launch 1B) Launch 2C) Both are the same.

Clicker Question Room Frequency BA

A block of mass m with initial speed v slides up a frictionless ramp of height h inclined at angle as shown. Assume no friction.

Whether the block makes it to the top depend on the angle . What do you think about this statement?A) True B) False

A block of mass m slides down a rough ramp of height h. Its initial speed is zero. Its final speed at the bottom of the ramp is v.

Which is the amount of thermal energy, Ethermal, released from the block’s motion down the ramp?

A) mgh 12mv2 B) mgh

12mv2

C) 12mv2 mgh D)

12mv2

E) mgh

h

m

KEi PEi Eithermal KE f PE f E f

thermal

0 mgh 0 12mv2 0 Ethermal

Ethermal mgh 12mv2

Clicker Question Room Frequency BA

Clicker Question Room Frequency BA

A pendulum consists of a mass m at the end of a string of length L. When the string is vertical, the mass has speed v0.

What is the maximum height h to which the mass swings?

Clicker Question Room Frequency BA

Ball 1 of mass m moving right with speed v bounces off ball 2 with mass M (M > m) and then moves left with speed 2v.

What is the magnitude of the impulse of Ball #1A) mv B) 2mv C) 3mv D) ½ mv E) 0

Clicker Question Room Frequency BA

A bullet of mass m traveling with initial speed v hits a block of mass M on a frictionless table. The bullet buries itself in the block, and the two together have a final velocity vf.

The total kinetic energy of the bullet+block after the collisions is _______ the total KE before the collision.

A) Greater thanB) Less thanC) Equal to

origin

Clicker Question Room Frequency BA

What is the torque about the origin?

A) r F sinB) r F cosC) zero

I miri2

i

Two light (massless) rods, labeled A and B, each are connected to the ceiling by a frictionless pivot as shown. Both rods are released from a horizontal position.Which one experiences the larger torque?A) A B) B C) Same

A FL Lmgsin B L2

2mgsin Lmgsin

θ

Fg = mgθ

F mgsin

Clicker Question Room Frequency BA

I miri2

i

Two light (massless) rods, labeled A and B, each are connected to the ceiling by a frictionless pivot as shown. Both rods are released from a horizontal position.

Which one has the larger moment of inertia?A) A B) B C) Same

IA mL2 IB (2m)L2

2

12mL2

Clicker Question Room Frequency BA

A small wheel and a large wheel are connected by a belt. The small wheel turns at a constant angular velocity ωS.

There is a bug S on the rim of the small wheel and a bug L on the rim of the big wheel? How do their speeds compare?

A) vS = vL

B) vS > vL

C) vS < vL

Clicker Question Room Frequency BA

A rock of mass m is twirled on a string in a horizontal plane.

The work done by the tension in the string on the rock is

The work done by the tension force is zero, because the force of the

tension in the string is perpendicular to the direction of the displacement:

W = F cos 90°= 0

TA) Positive B) NegativeC) Zero

Clicker Question Room Frequency BA

Roller Coaster ProblemClicker Question Room Frequency BA

If the car moving rightward at the top of this hill:A) The net force on the car is upward.

B) The net force on the car is downwardC) The net force on the car is zero

mg

N Fnet,y = N-mg = may = mv2/r

v

Approximately circular arc

Two paths lead to the top of a big hill. Path #1 is steep and direct and Path #2 is twice as long but less steep.

Both are rough paths and you push a box up each.

How much more potential energy is gained if you take the longer path?

A) none B) twice as much

C) four times as much D) half as much

h hd 2d

d 2 h2 4d 2 h2

#1 #2θ φ

PE mgh in both cases.

Clicker Question Room Frequency BA

A big ball of mass M = 10m and speed v strikes a small ball of mass m at rest.

Clicker Question Room Frequency BA

After the collision, could the big ball come to a complete stop and the small ball take off with speed 10 v?

A) Yes this can occurB) No, because it violates conservation of momentumC) No, because it violates conservation of energy

mvvmpinitial 10)10( mvvmp final 10)10(

22 5)10(21 mvvmKEinitial

22 50)10(21 mvvmKE final