Mechanical Advantage of Pulleys

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  • Topic: Force, Pulley, Mechanical advantage
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RYERSON UNIVERSITY
DEPARTMENT OF PHYSICS
LAB REPORT

TITLE OF EXPERIMENT
Mechanical Advantage of Pulleys

AUTHORS OF THIS REPORT:
SHAHIN ESMAEILIAZAD 500164540
LEILA FEIAMOHAMMADI 500115287

FOR
PCS 211---SECTION 07

EXPERIMENT PERFORMED ON (DATE): October3/ 2006

REPORT SUBMITTED ON (DATE): October 10/ 2006

TA’S NAME: Mr. SALAH SHARIF
OBJECTIVE AND BACKGROUND[pic]

This experience was performed to study different pulley arrangement and determine their advantage and efficiency. Pulley which is considered as a type of machine helps individual by changing the magnitude or direction of the force. In general, machines make the out put force or torque greater than input one. The magnitude of the force multiplication is called Mechanical Advantage. Here, two Mechanical Advantages and their differences will be discussed. One of them is Theoretical Mechanical Advantage and the other one is Actual Mechanical Advantage. Theoretical Mechanical Advantage, TMA, is defined as the ratio of the output force by the input (ideal) force.

[pic]

In contrast, Actual Mechanical Advantage, AMA, deal with the real situation which factional force and pulley’s weight will occur and the output force is always smaller than what expected.

[pic]

As far as work is concerned, in ideal case, input force work equals to output work:

[pic]

However, in real case the addition of the lost energy and output is equal to input force:

[pic]

The usage of machines is quite common and individual often check the efficiency of the machines or motors for better result. Efficiency can be defined as [pic], in terms of work, energy or power. The formula is as fallow:

[pic]

PROCEDURE AND OBSERVATION

EXPERIMENT I
MATERIAL: pulley, weight, holder, measured weight, rope
[pic]

PROCEDURE: A pulley system as figure (1) was set and then it checked if it was working properly. Different weights added to the holder for tree times as Load, and measured weight as Effort was obtained. This data is shown in calculation part. Effort = T1 = T

Load = T1 = T
In TMA, T1=T2; therefore, loaded part should be equal with effort part. T1= T2, as T2 is Effort and T1 is the load. EXPERIMENT II

MATERIAL: 2 pulleys, weight, holder, measured weight, rope

[pic]

PROCEDURE: A pulley system was set as figure (2) and then it checked if it was working properly. Hanging pulley was weighted: 16 g. later, different weights added to the holder for five times as Load, and measured weight as Effort was obtained. This data is shown in calculation part. .

Effort = T1 =T
Load = T1+T2=2T

EXPERIMENT III

MATERIAL: 3 pulleys, weight, holder, measured weight, rope

[pic][pic]

PROCEDURE: A pulley system was set as figure (3) and then it checked if it was working properly. Hanging pulley was weighted: 16 g. later, different weights added to the holder for five times as Load, and measured weight as Effort was obtained. This is shown in calculation part Effort = T1 = T

Load = T1 + T2 + T3 = 3T

CALCULATION

PART I
EXPERIMENT 1

|W (load) (g) |Effort (g) |[pic] | |100g |50 +52 =102g |0.98 | |200g |50 +155 =205g |0.98 | |300g |50 +256 =306g |0.98 |

Slope = AMA = 0.98

Efficiency = [pic]

[pic]
PART II
Experiment II

|[pic] |Effort (g) | [pic] | |300g+16g =316g |166g |1.90...
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