Moments














Moments : āĻŽā§āĻšā§‚āĻ°ā§āϤ : A moment is the turning effect of a force about a point or pivot. (āĻŽā§āĻšā§‚āĻ°ā§āϤ āĻšā§ˆāϛ⧇ āϕ⧋āύ⧋ āĻŦāĻŋāĻ¨ā§āĻĻ⧁ āĻŦāĻž pivot-ā§° āϚāĻžā§°āĻŋāĻ“āĻĢāĻžāϞ⧇ āĻŦāϞ⧰ āĻ˜ā§‚ā§°āĻŖā§€āϝāĻŧāĻž āĻĒā§ā§°āĻ­āĻžā§ąāĨ¤)


Moment of a Force (āĻŦāϞ⧰ āĻŽā§āĻšā§‚āĻ°ā§āϤ)


Moment of a force about a point = Force × Perpendicular distance from the pivot.

āϕ⧋āύ⧋ āĻŦāĻŋāĻ¨ā§āĻĻ⧁⧰ āϚāĻžā§°āĻŋāĻ“āĻĢāĻžāϞ⧇ āĻŦāϞ⧰ āĻŽā§āĻšā§‚āĻ°ā§āϤ = āĻŦāϞ × pivot-ā§° āĻĒā§°āĻž āϞāĻŽā§āĻŦ āĻĻā§‚ā§°āĻ¤ā§āĻŦāĨ¤


Formula / āϏ⧂āĻ¤ā§ā§° : Momen = F×d


Where / āϝ’āϤ : = Force (āĻŦāϞ), = Perpendicular distance from pivot (pivot-ā§° āĻĒā§°āĻž āϞāĻŽā§āĻŦ āĻĻā§‚ā§°āĻ¤ā§āĻŦ)


Principle of Moments : āĻŽā§āĻšā§‚āĻ°ā§āϤ⧰ āύ⧀āϤāĻŋ

For a body in balance: Clockwise moments = Anticlockwise moments


āϏāĻŽāϤāĻžāϤ āĻĨāĻ•āĻž āĻŦāĻ¸ā§āϤ⧁⧰ āĻ•ā§āώ⧇āĻ¤ā§ā§°āϤ: Clockwise āĻŽā§āĻšā§‚āĻ°ā§āϤ = Anticlockwise āĻŽā§āĻšā§‚āĻ°ā§āϤ


Example / āωāĻĻāĻžāĻšā§°āĻŖ : A seesaw balances when moments on both sides are equal. (āĻĻ⧁āϝāĻŧā§‹āĻĢāĻžāϞ⧰ āĻŽā§āĻšā§‚āĻ°ā§āϤ āϏāĻŽāĻžāύ āĻšāϞ⧇ seesaw āϏāĻŽāϤāĻžāϤ āĻĨāĻžāϕ⧇āĨ¤)

Applications / āĻŦā§āĻ¯ā§ąāĻšāĻžā§° : i. Seesaw (āĻĻā§‹āϞāύāĻž), ii. Spanner (āĻ¸ā§āĻĒ⧇āύāĻžā§°), iii. Door handle (āĻĻā§ā§ąāĻžā§°ā§° āĻšāĻžāϤāϞ)

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Moments – 2 Marks Questions with Answers āĻŽā§āĻšā§‚āĻ°ā§āϤ – ⧍ āύāĻŽā§āĻŦā§°ā§° āĻĒā§ā§°āĻļā§āύ⧋āĻ¤ā§āϤ⧰


1. What is a moment of force ? āĻŦāϞ⧰ āĻŽā§āĻšā§‚āĻ°ā§āϤ āĻ•āĻŋ ?

Ans: The moment of a force is the turning effect produced by a force about a point or pivot. āωāĻ¤ā§āϤ⧰: āĻŦāϞ⧰ āĻŽā§āĻšā§‚āĻ°ā§āϤ āĻšā§ˆāϛ⧇ āϕ⧋āύ⧋ āĻŦāĻŋāĻ¨ā§āĻĻ⧁ āĻŦāĻž pivot-ā§° āϚāĻžā§°āĻŋāĻ“āĻĢāĻžāϞ⧇ āĻŦāϞ⧰ āĻ˜ā§‚ā§°āĻŖā§€āϝāĻŧāĻž āĻĒā§ā§°āĻ­āĻžā§ąāĨ¤


2. Write the formula of moment. āĻŽā§āĻšā§‚āĻ°ā§āϤ⧰ āϏ⧂āĻ¤ā§ā§° āϞāĻŋāĻ–āĻžāĨ¤

Ans: Moment = F×d . Moment is equal to force multiplied by perpendicular distance from the pivot.


āωāĻ¤ā§āϤ⧰: āĻŽā§āĻšā§‚āĻ°ā§āϤ = āĻŦāϞ × pivot-ā§° āĻĒā§°āĻž āϞāĻŽā§āĻŦ āĻĻā§‚ā§°āĻ¤ā§āĻŦāĨ¤


3. State the principle of moments. āĻŽā§āĻšā§‚āĻ°ā§āϤ⧰ āύ⧀āϤāĻŋ āωāĻ˛ā§āϞ⧇āĻ– āϕ⧰āĻžāĨ¤

Ans: For a body in equilibrium, clockwise moments are equal to anticlockwise moments. āωāĻ¤ā§āϤ⧰: āϏāĻŽāϤāĻžāϤ āĻĨāĻ•āĻž āĻŦāĻ¸ā§āϤ⧁⧰ āĻ•ā§āώ⧇āĻ¤ā§ā§°āϤ clockwise āĻŽā§āĻšā§‚āĻ°ā§āϤ āφ⧰⧁ anticlockwise āĻŽā§āĻšā§‚āĻ°ā§āϤ āϏāĻŽāĻžāύ āĻšāϝāĻŧāĨ¤


4. What is pivot ? Pivot āĻ•āĻŋ ?

Ans: Pivot is the fixed point about which a body turns. āωāĻ¤ā§āϤ⧰: Pivot āĻšā§ˆāϛ⧇ āϏ⧇āχ āĻ¸ā§āĻĨāĻŋā§° āĻŦāĻŋāĻ¨ā§āĻĻ⧁ āϝāĻžā§° āϚāĻžā§°āĻŋāĻ“āĻĢāĻžāϞ⧇ āĻŦāĻ¸ā§āϤ⧁ āĻ˜ā§‚ā§°ā§‡āĨ¤


5. Name one application of moments. āĻŽā§āĻšā§‚āĻ°ā§āϤ⧰ āĻāϟāĻž āĻŦā§āĻ¯ā§ąāĻšāĻžā§° āϞāĻŋāĻ–āĻžāĨ¤

Ans: Seesaw works on the principle of moments. āωāĻ¤ā§āϤ⧰: Seesaw-āĻ āĻŽā§āĻšā§‚āĻ°ā§āϤ⧰ āύ⧀āϤāĻŋāϤ āĻ•āĻžāĻŽ āϕ⧰⧇āĨ¤














Moments – 5 Marks Questions with Answers : āĻŽā§āĻšā§‚āĻ°ā§āϤ – ā§Ģ āύāĻŽā§āĻŦā§°ā§° āĻĒā§ā§°āĻļā§āύ⧋āĻ¤ā§āϤ⧰


1. Define moment of force and write its formula. āĻŦāϞ⧰ āĻŽā§āĻšā§‚āĻ°ā§āϤ⧰ āϏāĻ‚āĻœā§āĻžāĻž āĻĻāĻŋāϝāĻŧāĻž āφ⧰⧁ āϏ⧂āĻ¤ā§ā§° āϞāĻŋāĻ–āĻžāĨ¤

Ans: The moment of force is the turning effect produced by a force about a point or pivot.


Formula: Moment = F × d


Where: = Force, = Perpendicular distance from pivot


āωāĻ¤ā§āϤ⧰: āĻŦāϞ⧰ āĻŽā§āĻšā§‚āĻ°ā§āϤ āĻšā§ˆāϛ⧇ āϕ⧋āύ⧋ pivot-ā§° āϚāĻžā§°āĻŋāĻ“āĻĢāĻžāϞ⧇ āĻŦāϞ⧰ āĻ˜ā§‚ā§°āĻŖā§€āϝāĻŧāĻž āĻĒā§ā§°āĻ­āĻžā§ąāĨ¤


āϝ’āϤ, = āĻŦāϞ, = pivot-ā§° āĻĒā§°āĻž āϞāĻŽā§āĻŦ āĻĻā§‚ā§°āĻ¤ā§āĻŦ


2. Explain the principle of moments with an example. āωāĻĻāĻžāĻšā§°āĻŖāϏāĻš āĻŽā§āĻšā§‚āĻ°ā§āϤ⧰ āύ⧀āϤāĻŋ āĻŦā§āϝāĻžāĻ–ā§āϝāĻž āϕ⧰āĻžāĨ¤

Ans: The principle of moments states that for a body in equilibrium, clockwise moments are equal to anticlockwise moments. For example, a seesaw balances when the turning effects on both sides are equal.


āωāĻ¤ā§āϤ⧰: āĻŽā§āĻšā§‚āĻ°ā§āϤ⧰ āύ⧀āϤāĻŋ āĻ…āύ⧁āϏ⧰āĻŋ āϏāĻŽāϤāĻžāϤ āĻĨāĻ•āĻž āĻŦāĻ¸ā§āϤ⧁⧰ āĻ•ā§āώ⧇āĻ¤ā§ā§°āϤ clockwise āφ⧰⧁ anticlockwise āĻŽā§āĻšā§‚āĻ°ā§āϤ āϏāĻŽāĻžāύ āĻšāϝāĻŧāĨ¤ āωāĻĻāĻžāĻšā§°āĻŖāĻ¸ā§āĻŦā§°ā§‚āĻĒ⧇, seesaw-ā§° āĻĻ⧁āϝāĻŧā§‹āĻĢāĻžāϞ⧰ āĻ˜ā§‚ā§°āĻŖā§€āϝāĻŧāĻž āĻĒā§ā§°āĻ­āĻžā§ą āϏāĻŽāĻžāύ āĻšāϞ⧇ āχ āϏāĻŽāϤāĻžāϤ āĻĨāĻžāϕ⧇āĨ¤


3. What factors affect the moment of force ? āĻŦāϞ⧰ āĻŽā§āĻšā§‚āĻ°ā§āϤ āϕ⧋āύ āϕ⧋āύ āĻ•āĻžā§°āϕ⧇ āĻĒā§ā§°āĻ­āĻžā§ąāĻŋāϤ āϕ⧰⧇ ?

Ans: Moment of force depends on: i. Magnitude of force ii. Perpendicular distance from pivot


āωāĻ¤ā§āϤ⧰: āĻŦāϞ⧰ āĻŽā§āĻšā§‚āĻ°ā§āϤ āύāĻŋā§°ā§āĻ­ā§° āϕ⧰⧇: ā§§āĨ¤ āĻŦāϞ⧰ āĻŽāĻžāύ  ⧍āĨ¤ pivot-ā§° āĻĒā§°āĻž āϞāĻŽā§āĻŦ āĻĻā§‚ā§°āĻ¤ā§āĻŦ


4. Mention two applications of moments. āĻŽā§āĻšā§‚āĻ°ā§āϤ⧰ āĻĻ⧁āϟāĻž āĻŦā§āĻ¯ā§ąāĻšāĻžā§° āωāĻ˛ā§āϞ⧇āĻ– āϕ⧰āĻžāĨ¤

Ans: i. Seesaw  ii. Spanner


5. Why is a long spanner easier to use than a short spanner ? āĻĻā§€āϘāϞ spanner āĻŦā§āĻ¯ā§ąāĻšāĻžā§° āϕ⧰āĻž āϏ⧰⧁ spanner-āϤāĻ•ā§ˆ āĻ•āĻŋāϝāĻŧ āϏāĻšāϜ ?

Ans: A long spanner produces greater moment because the perpendicular distance from the pivot is larger.


āωāĻ¤ā§āϤ⧰: āĻĻā§€āϘāϞ spanner-āϤ pivot-ā§° āĻĒā§°āĻž āĻĻā§‚ā§°āĻ¤ā§āĻŦ āĻŦ⧇āĻ›āĻŋ āĻšāϝāĻŧ, āϏ⧇āϝāĻŧ⧇āĻšā§‡ āĻ…āϧāĻŋāĻ• āĻŽā§āĻšā§‚āĻ°ā§āϤ āĻ‰ā§ŽāĻĒāĻ¨ā§āύ āĻšāϝāĻŧ āφ⧰⧁ āĻŦā§āĻ¯ā§ąāĻšāĻžā§° āϏāĻšāϜ āĻšāϝāĻŧāĨ¤