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Pulleys Lab

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Pulleys Lab

Question

How do Pulleys effect the input/output of a system? What is the ideal mechanical advantage of a system?

Concept

In an ideal system of pulleys, all the energy is transferred from the input to the output without any losses to friction and other forces. Theoretically the efficiency of a system should always be 100% but in real life applications it will always be less than 100% due to miscellaneous forces. The IMA of a system can be found by dividing the distance moved for the force by the distance moved for the load. In The work for input and output would be equal to the force (N) x the distance moved(m).

Work input = FeDe         IMA = De/Dr

Work output = FrDr        Efficiency = Work output/ Work input

Hypothesis

If there are more pulleys present in a system, then I will increase the IMA, therefore changing the ratio of force to distance of the load. In real life applications, the efficiency of a system will always be less than 100% due to friction and other forces.

Materials

  • 2 single pulleys                        
  • 2 double pulleys                         
  • Set of hooked metric masses         
  • Meter stick
  • String
  • Spring scale
  • Pulley support

Procedure

  1. Set up the system of pulleys according to the diagrams given.
  2. Use the Spring scale to move the load a certain distance from the other end of the system.
  3. Record the distance moved by the load and the distance moved by the force.
  4. Record the forces of the mass and the spring scale.
  5. Repeat steps 1 - 4 with 2 different masses for each pulley system.
  6. Place all the data collected on a chat.



Data Collection

Table 1

Pulley

Arrangement

Mass raised

(kg)

Weight (w)

Of mass (N)

Height (h) mass is raised (m)

Force (F) of spring scale (N)

Distance (d) through which force acts (m)

(a)

0.5kg

4.9N

.17m

4.9N

.165m

(a)

0.2kg

1.96N

.21m

1.8N

.22m

(b)

0.5kg

4.9N

.135m

2.6N

.265m

(b)

0.2kg

1.96N

.175m

1.0N

.34m

(c)

0.5kg

4.9N

.045m

2.4N

.09m

(c)

0.2kg

1.96N

.035m

.85N

.07m

(d)

0.5kg

4.9N

.04m

1.1N

.16m

(d)

0.2kg

1.96N

.065m

0.6N

.26m


Table 2

Pulley

Arrangement

Work output (wh)

(J)

Work input (fd)

(J)

IMA

(De/Df)

MA

Number of lifting stands

Efficiency

(%)

(a)

0.833J

0.8085J

0.97

1

103%

(a)

0.4116J

0.396J

1.048

1

103%

(b)

0.6615J

0.689J

1.96

2

96%

(b)

0.343J

0.34J

1.048

2

101%

(c)

0.2205J

0.216J

2

2

102%

(c)

0.0686J

0.0595J

2

2

115%

(d)

0.196J

0.176J

4

4

111%

(d)

0.1274J

0.156J

4

4

82%

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