Question

PART 1

You have three tasks.

Trial I:   Balance the stick with the fulcrum at its center of gravity. Attach a 200 g mass, plus hanger #1, at Location A on the meter stick and calculate where to attach a 200 g mass, plus hanger #2, to balance it.

Trial II:    Balance the stick with the fulcrum at its center of gravity. Attach a 500 g mass, plus hanger #1, at Location B and determine where to attach a 200 g mass, plus hanger #2, to balance it.

Trail III:     Move the fulcrum to Location C, even though the meter stick does not balance. Attach a 200 g mass with hanger #1 at Location A and calculate where to place a 200 g mass with hanger #2 to make it all balance.

DATA

Center of gravity: ______ cm

Mass of stick (including attached fulcrum):______ g

Mass of hanger #1: ______ g

Mass of hanger #2: _______ g

Let the 0 cm mark on the meter stick be on the left, 100 cm mark on the right.

Any mass hung at location A or B gives ccw torque.

Let “Mass 1” be the mass of hanger #1 plus the mass attached to it.

Let “Location 1” be the location (cm marked on the meter stick) of hanger #1.

Let “Mass 2” be the mass of hanger #2 plus the mass attached to it.

Let “Location 2” be the location (cm marked on the meter stick) of hanger #2.

                                                τ = r⊥ * F = r⊥ * m * g

ANALYSIS:

	Mass 1	Location 1	Lever Armfrom fulcrum to Location 1	CCW Torque From Mass 1 at Location 1	Torque from off-balance weight of the meter stick	CW Torque Needed from Mass 2 to balance	Mass 2	Location 2 From fulcrum to Location 2	Lever Arm
I
II
III

REPORT DUE IN 1 WEEK

Submit the conclusion with your results (NEATLY ORGANIZED), summarizing what you have demonstrated about the net torque acting on a system in rotational equilibrium, using terms “torque”, lever arm”, and balance.

Extra Credit:  Diving Board Model [up to 10 pts]

         Assemble a model diving board and determine the location on the board where it will begin to tip.  Place a meter stick (or a ruler)  on a level table so that ~25 cm (or 25% , in the case of the ruler) extends beyond the edge of the table as shown below.   Now move a mass (ie, stack of coins, rock, etc..)  along the extended portion of the meter stick until it begins to tip.

Record the mass of the meter stick, the length of the piece overhanging the table and the location of the center of the mass. Weigh the meter stick (or the ruler) and the mass.

Present a data table with your measurements.

Then present the theoretical calculations to determine the position of the mass that makes the meter stick begin to tip. Equations and calculations must be clearly shown, in organized steps.

Finally, make an analysis table comparing the measured and theoretical values.

Answer 1