PhysicsLabI_exp3

7/26/2019 PhysicsLabI_exp3

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EXPERIMENT :3

TORQUES EXPERIMENT

Purpose :Torque measures the tendency of a force to rotate an object about an axis. The principles

of applying ana balancing torques are explored in this investigation.

Materials:

Metal bar, clamp, a ruler , different standart mass ( 10,50,100,150, gr ) ,1 suspend apparatus.

Introduction : A single particle off mass m whose location with respect to the origin O of an inertial

reference frame is described by a position vector . Let force act on particle ana let its linearmomentum be . Here are two definitions and a relation between them:

i. The torque about O acting on a particle due to the force ,

ii.

The angular momentum of of the particle about O,

iii. Newtons second law of motion for a single particle, in rotational form,

Metal Bar

10g 20g

L(1) L(2)L(0)


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PROCEDURES

i.) Balancing torques on a metal bar.

Suspend a (metal bar) from an overhead support as shown in diagram. Slide the metal bar

along the clamp until you find a position for the clamp where the metal bar balances horizontally.

Record the position of this point of suspension L(0)in the data chart.

Exactly 15.0 cm to the right of the point of suspension, hang a 10 g standart mass. The

weight of the standart mass exerts a force on the metal bar that causes it to rotate around the point

of suspension. Observe whether the torque produced by this force is clockwise or counterclockwise.

Record the position L(1) via a ruler and weight f(1) of the Standard mass in data chart, using the

approximation that a mass of 10 g weighs 0,1 N.

Hang a 20 g standart mass on the left side of the metal bar and adjust its position until the

metal bar is balanced horizontally. Record this position L(2) and the weigth f(2)of the standart mass

(0,2N). Also note whether the weight of the mass creates a clockwise or counterclocwise torque

around the point of suspension.

Repeat the above procedure, using a variety of positions for the different standart masses

ana finding the corresponding position of the 30 g mass that will balance the metal bar

horizontally. Substitute different known masses on each side of the point of suspension. Repeat the

above precedures.

DATA and ANALYSIS

Location of point of suspension L(0)= .. meter.

TABLE I

TRIAL 1 2 3 4 5 6 7 8

Mass (g) m(1)

Position of Mass (m) L(1)

Distance from point of suspension (m) X(1)

Force (N) f(1)

Torque (Nm) T(1)

Mass (g) m(2)

Position of Mass (m) L(2)

Distance from point of suspension (m) L(2)

Force (N) f(2)

Torque (Nm) T(2)

Percent Error E%


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ii.) Weighing an Unknown.

After making sure the metal bar is balanced horizontally when nothing is hung from it, hang a

known mass on one side of the metal bar and an object of unknown mass on the other side.

Adjust the position of the unknown until the metal bar is again balanced horizontally.

Determine and record the positions of the two objects.

Move the known mass to different new positions. At each new position, move the unknown

until the bar is rebalanced ana recor the positions of the known and unknown.

DATA and ANALYSIS

Location of point of suspension L(0) = .. cm.

Known mass m =g

TABLE II

REFERENCES

1. Experiments for Physics Labs Herbert H.Gottlies

TRIAL 1 2 3 4 5 6 7 8

KnownTorque

Position of Mass (m)

L(1)

Distance from point of suspension

(m) X(1)

Force (N)

f(1)

Torque (Nm)

T(1)

UnknownTorque

Mass (g)

m(2)

Position of unknown mass (m)

L(2)

Distance from point of suspension

(m) X(2)

Torque (Nm)

T(2)

Calculated weight (N) %E

Measured weight (N)

Percent Error E%


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REPORT

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PhysicsLabI_exp3