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CISCEICSE ICSE Class 6
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Syllabus

A Pulley

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Topics

  • Introduction
  • Experiment

Introduction:

A pulley is a simple machine that consists of a wheel on an axle or shaft that is designed to support movement and change the direction of force through a taut cable, rope, belt, or chain. The basic idea of a pulley system is to make it easier to lift heavy loads or apply force efficiently.

  • Pulleys function by changing the direction of the force applied to the rope or cable. This allows for more effective use of human or mechanical power.
  • For example, pulling down on a rope can lift an object that is attached to the other end upward.

Types of Pulleys:

  1. Fixed Pulley: This type of pulley is mounted in one position and doesn’t move with the load. It changes the direction of the force applied, allowing you to pull down to lift an object up.
  2. Movable Pulley: In this system, the pulley moves with the load. A movable pulley offers a mechanical advantage; it reduces the amount of force needed to lift an object but increases the distance over which the force must be applied.
  3. Compound Pulley: A combination of fixed and movable pulleys that provides a greater mechanical advantage, making it much easier to lift heavier loads with less effort.

Experiment

1. Aim: This experiment aims to demonstrate how a pulley can lift a weight with less effort by changing the direction of the applied force.

2. Requirements: pencil, sticking tape, an empty reel of thread (acts as the pulley), half a meter of thick thread, small weight (such as an eraser), and play-dough.

3. Procedure:

  • Place the pencil horizontally on the table to extend over the edge. Use sticking tape to secure the pencil firmly to the table.
  • Slide the reel of thread over the part of the pencil that juts out, making sure it can rotate freely.
  • Place a lump of play-dough on the tip of the pencil to prevent the reel from sliding off.
  • Tie one end of the thick thread to the weight and place the other end over the reel.
  • Hold the loose end of the thread that does not have the weight and pull it downward.

4. Observation: When the thread is pulled down, the weight on the other end lifts up.

5. Conclusion: The pulley system allows you to exert force in a downward direction to lift a weight upwards, which is generally easier than lifting directly. This experiment shows that a pulley changes the direction of the force applied, making it more convenient to lift the objects.

A pulley in everyday life

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Related QuestionsVIEW ALL [95]

Name a machine which is used to:

change the direction of force applied.

_______ is a machine made up of wheel and rope.

Answer the following in short.

Explain the various functions that a machine can perform.

Is the above pulley system an ideal machine or not?

Give reason for the following:

 The efficiency of a pulley is always less than 100%

A type of single pulley is very often used as a machine even though it does not give any gain in mechanical advantage. Name the type of pulley used.

Select the correct alternative:

A pulley is used because of it

The diagram below shows an arrangement of three pulleys A, B, and C. The load is marked as L and the effort as E.

  1. Name the Pulleys A, B, and C.
  2. Mark in the diagram the directions of load (L), effort (E) and tension T1 and T2 in the two strings.
  3. How are the magnitudes of L and E related to the tension T1?
  4. Calculate the mechanical advantage and velocity ratio of the arrangement.
  5. What assumptions have you made in parts (c) and (d)?

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