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CISCEICSE ICSE Class 6
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Syllabus

A Lever

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Topics

  • Introduction
  • Experiment 1
  • Experiment 2
  • Experiment 3

Introduction:

A lever is a simple machine that helps lift or move heavy objects using less effort. It consists of a long rod or bar. Levers make lifting heavy loads easier by reducing the effort needed. They are used in many tools and machines to perform different tasks.

1. Parts of a Lever

  • Fulcrum: This is the point where the lever is supported or pivots. The lever rotates around the fulcrum.
  • Load: The weight or object that the lever is trying to lift or move. The distance from the fulcrum to the load is called the load arm.
  • Effort: The force applied to the other end of the lever to lift or move the load. The distance from the fulcrum to where the effort is applied is called the effort arm.

2. Working of a Lever

The lever rotates around the fulcrum when effort is applied to one side. By applying force (effort) on one end of the lever, it lifts or moves the load on the other end. The longer the effort arm, the less force is needed to lift the load. For example: crowbar, seesaw, scissors, etc.

Experiment 1

1. Aim: To understand how a first-order lever works and observe how the length of the effort arm affects the force needed to lift a load.

2. Requirements: pencil (fulcrum), ruler (lever), paperweight or small heavy object (load), measuring tape (optional).

3. Procedure

  • Place the pencil horizontally on the table as the fulcrum.
  • Place the ruler on top of the pencil at a right angle, with one end holding the paperweight (load).
  • To lift the weight, press the opposite end of the ruler (effort).
  • Move the paperweight 4 cm farther from the pencil each time and observe the amount of force needed to lift it.

4. Conclusion

As the effort arm (the distance between the fulcrum and the point where force is applied) increases, less force is required to lift the paperweight. This setup is an example of a first-order lever, where the fulcrum is placed between the load and effort.

Lifting a paperweight

Experiment 2

1. Aim: To demonstrate how a bottle opener (lever) removes a tight-fitting cap from a bottle, identify the roles of fulcrum, load, and effort in the process.

2. Requirements: a bottle with a cap and bottle opener.

3. Procedure

  • Place the bottle on a stable surface.
  • Position the bottle opener so that the middle part (the fulcrum) rests on the edge of the cap.
  • Hold the end of the opener farthest from the cap and apply downward force. This is where you apply the effort.
  • As you press down on the opener, watch the cap (the load) lift off the bottle.

4. Identification of parts

  • Fulcrum: The part of the opener that rests directly on the cap, allowing the tool to pivot.
  • Load: The bottle cap, which is the object being lifted.
  • Effort: The force applied at the opposite end of the opener from the cap.

5. Conclusion: This experiment uses the bottle opener as a first-order lever to remove a bottle cap. The fulcrum is in the middle, with the load (cap) on one side and the effort applied on the other. This setup reduces the force needed to lift the cap, demonstrating how levers provide a mechanical advantage, making it easier to perform tasks that would require more force.

Removing the lid

Experiment 3

1. Aim: To understand how tongs operate as a type of lever, specifically demonstrating the roles of the fulcrum, load, and effort.

2. Requirements: a pair of tongs, an object to pick up (such as a small ball or a piece of fruit)

3. Procedure

  • Place the object on a flat surface.
  • Hold the tongs with one hand near the hinge (which acts as the fulcrum).
  • Squeeze the tongs in the middle part of the arms. This is where the effort is applied.
  • Observe how the ends of the tongs (where the object is) come together to lift the object. This end represents the load.

4. Identification of parts

  • Fulcrum: The hinge or the central pivot point of the tongs.
  • Load: The object being lifted by the tongs.
  • Effort: The force applied by your hand in the middle of the tongs’ arms.

5. Conclusion: The tongs function as a third-order lever (also known as a Class III lever) where the effort is applied between the fulcrum and the load. This type of lever is designed for precision and control rather than force amplification. By applying effort in the middle, the tongs allow for precise control over the gripping and lifting of objects, demonstrating how levers can be used to enhance both force and accuracy in everyday tools.

Picking up an object

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Related QuestionsVIEW ALL [50]

The following belong to which class of lever?

Nutcracker

When we want to use a machine as a force multiplier, which class of lever should we preferably use? Give a simple diagram of such a lever.

The length of a nut-cracker is 12 cm. A nut, when kept at a distance of 4 cm from its fulcrum, requires an effort of 100 gf to crack it. What force will be required to crack the nut without using the nut-cracker?

In the following diagram of a wheelbarrow, mark the fulcrum (F) and indicate the directions of load (L) and effort (E) with arrows.

What class of lever is it? Give one more example of the same class of lever.

The following are an example of levers. State the class of lever to which each one belongs giving the relative positions of Load (L), Effort (E), Fulcrum (F):
(i) Scissors (ii) Sugar tongs (iii) Nutcracker (iv) Pliers.

A lever of length 9 cm has its load arm 5 cm long and the effort arm is 9 cm long.

  1. To which class does it belong?
  2. Draw a diagram of the lever showing the position of fulcrum F and directions of both the load L and effort E.
  3. What is the mechanical advantage and velocity ratio if the efficiency is 100%?
  4. What will be the mechanical advantage and velocity ratio if the efficiency becomes 50%?

Define Lever

The following belong to which class of lever?

An oar of a boat

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