Class 9 Physics Edition

The Power of Levers

Unlocking the Secrets of the Third-Class Lever

Ever wondered how you can throw a ball at high speeds, sweep a floor rapidly, or lift items using tweezers? It is all thanks to simple machines operating in plain sight.

NCERT Core Concept: Understand forces, pivot points, mechanical advantage, and how biology mimics physics!

Press Next or Use your Right Arrow Key to start

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Lever Basics: The "FLE" Secret

Every lever on Earth has three essential components, no matter its shape:

  • Fulcrum (F): The fixed pivot point around which the lever rotates.
  • Load (L): The object/resistance force you want to move or overcome.
  • Effort (E): The input force you apply to make things move.

Use the Easy NCERT "F-L-E" Hack:

F

Class 1
Fulcrum in Middle

L

Class 2
Load in Middle

E

Class 3
Effort in Middle

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The Third-Class Lever

In a Class 3 lever, the Effort is sandwiched between the Fulcrum and the Load.

Key Characteristics:

  • The effort force acts in the same direction as the movement.
  • The effort arm is always shorter than the load arm.

Because the effort arm is shorter, you must exert more force than the load itself to lift it. Let's see why we would ever want to do that!

Force Relationship Layout:

Fulcrum (Pivot) โž” Effort (Input) โž” Load (Output)

"The closer the effort is to the pivot, the more power you need, but the faster the load will travel!"

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Interactive Lever Simulator

Drag the slider below to apply effort. Observe how the Load travels a much larger distance and moves much faster than the Effort.

FULCRUM
EFFORT (Middle)
LOAD 10 kg
Rest Position Pull Upward

Distance Multiplying Effect: Notice how a small push in the middle yields a massive sweep at the tip!

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Mechanical Advantage (M.A.)

In physics, Mechanical Advantage measures how much force multiplier a machine gives you.

Formula

M.A. = Effort Arm / Load Arm

Always Less Than 1 (< 1)

Since the Effort Arm (distance from Fulcrum to Effort) is shorter than the Load Arm, the M.A. is always less than 1.

If M.A. < 1, why do we use it?

  • Speed Multiplier: The load moves much faster than the effort.
  • Distance Multiplier: A tiny movement of your muscle translates to a wide reach at the tip.
  • Precision Control: It allows for delicate handling of objects (like tweezers).

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Real-Life Examples & Human Body

We use third-class levers every single day without realizing it!

The Human Forearm

Your arm is a biological Third-Class Lever!

  • Fulcrum: Your elbow joint.
  • Effort: Bicep muscle inserting just past the elbow.
  • Load: The weight held in your hand.
๐Ÿงน
Brooms

Top hand pivots, bottom hand pushes effort.

๐ŸŽฃ
Fishing Rods

Wrist acts as pivot; other hand applies central force.

๐Ÿฅข
Tweezers / Tongs

Joined at back end; fingers squeeze in the middle.

๐Ÿ
Sports Equipment

Cricket bats and hockey sticks multiply hand speed.

Slide 6 of 7

Project Team

This interactive physics presentation was built and designed by:

  • Yuvan
  • p2
  • p3
  • Rachit
  • p4
  • p5
๐ŸŽ“

Thank You!

Class 9 Physics Practical Application Project.

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