AP PHY_Torque

1) What is the total amount of kinetic energy the mass has as it swings through the equilibrium position?

a. 11J b. 94J c. 110J d. 920J

2)

3) An object is dropped from rest from a certain height. Air resistance is negligible. After falling a distance d, the object’s kinetic energy is proportional to which of the following?

4) A plane is traveling at 200m/s following the arc of a vertical circle of Radius R. At the top of its path, the passengers experience weightlessness. To one significant figure, what is the value of R?

a) 200m b)1000m c) 2000m d) 4000m

F = mv2/r

Next warm up ask about wrench

AnnouncementsAP:

AgendaAP: •Finish Test•Torque Intro•Torque Notes•Torque Simulation•Torque Practice•Torque Exit ticket

Unit 8 – Torque

Textbook Chapter 11:

11/28: Section 11-1 and 11-3

Homework:

page 343: 3, 18 ( p315) , 23

Torque IntroductionMaterials: Shower Track

Mass Hanger/Mass

Step 1: Hold track outward, get a feel for the effort it takes to hold it up

Step 2: Hang the 1000g mass next to your hands

Step 3: Slide mass ~10cm every 5 seconds

Step 4: See how far out you can support the mass. If you reach then end, time how long you can hold it!

Torque Introduction• Torque is analogous to a force.

Force TorqueLinear Acceleration Angular Acceleration

Torque

Torque Introduction

• The “distance” of the force also matters.

•Lever Arm: The distance between the pivot point and the force.

Torque Introduction

• The “angle” of the force also matters.

10N10N

Torque Introduction

• The “angle” of the force also matters.• Use the sin component of the force

•Measure the angle from the BOARD to the FORCE

10N10N

Torque Introduction

torque = distance from axis of rotation x force x sin (angle between r and F)

Units for torque: Nm (Newton-meters)

sinrF

Equilibrium – Up to the board

•Net Force = Zero No acceleration

•Net Torque = Zero No rotation

• Clockwise = (+) Counterclockwise = (-)

Sample – What is the mass of the boy?

Tnet =

Tnet =

Sample – Where does the 5kg mass go?

Tnet =

Torque Lab

•Partner up.

•Google “Phet Balancing Act”

•Run simulation

•Step 1: 5 minute “mess around”…write down 3 things that you notice

•Step 2: Complete lab. Graded for correctness!

Exit Ticket 1

A meter stick is pivoted at the 0.50 m line. A 3.0 kg object is hung from the 0.40 m line. Where should a 6.0 kg object be hung to achieve equilibrium?

Exit 2 Ticket

To weigh a fish a person hangs a tackle box of mass 6 kilograms and a cooler of mass 10 kilograms from the ends of a uniform rigid pole that is suspended by a rope attached to its center. The system balances when the fish hangs at a point 1/4 of the rod’s length from the tackle box. What is the mass of the fish?

6kg 10kg

Angle Example 1:

In which of the diagrams is the torque about point O equal to the torque about point X

Angle Example 1:

You try angle practice