Moments
Moments : āĻŽā§āĻšā§āϰā§āϤ : A moment is the turning effect of a force about a point or pivot. (āĻŽā§āĻšā§āϰā§āϤ āĻšā§āĻā§ āĻā§āύ⧠āĻŦāĻŋāύā§āĻĻā§ āĻŦāĻž pivot-ā§° āĻāĻžā§°āĻŋāĻāĻĢāĻžāϞ⧠āĻŦāϞ⧰ āĻā§ā§°āĻŖā§āϝāĻŧāĻž āĻĒā§ā§°āĻāĻžā§ąāĨ¤)
Moment of a Force (āĻŦāϞ⧰ āĻŽā§āĻšā§āϰā§āϤ)
Moment of a force about a point = Force × Perpendicular distance from the pivot.
āĻā§āύ⧠āĻŦāĻŋāύā§āĻĻā§ā§° āĻāĻžā§°āĻŋāĻāĻĢāĻžāϞ⧠āĻŦāϞ⧰ āĻŽā§āĻšā§āϰā§āϤ = āĻŦāϞ × pivot-ā§° āĻĒā§°āĻž āϞāĻŽā§āĻŦ āĻĻā§ā§°āϤā§āĻŦāĨ¤
Formula / āϏā§āϤā§ā§° : Momen = F×d
Where / āϝ’āϤ : F = Force (āĻŦāϞ), d = Perpendicular distance from pivot (pivot-ā§° āĻĒā§°āĻž āϞāĻŽā§āĻŦ āĻĻā§ā§°āϤā§āĻŦ)
Principle of Moments : āĻŽā§āĻšā§āϰā§āϤ⧰ āύā§āϤāĻŋ
For a body in balance: Clockwise moments = Anticlockwise moments
āϏāĻŽāϤāĻžāϤ āĻĨāĻāĻž āĻŦāϏā§āϤā§ā§° āĻā§āώā§āϤā§ā§°āϤ: Clockwise āĻŽā§āĻšā§āϰā§āϤ = Anticlockwise āĻŽā§āĻšā§āϰā§āϤ
Example / āĻāĻĻāĻžāĻšā§°āĻŖ : A seesaw balances when moments on both sides are equal. (āĻĻā§āϝāĻŧā§āĻĢāĻžāϞ⧰ āĻŽā§āĻšā§āϰā§āϤ āϏāĻŽāĻžāύ āĻšāϞ⧠seesaw āϏāĻŽāϤāĻžāϤ āĻĨāĻžāĻā§āĨ¤)
Moments – 2 Marks Questions with Answers āĻŽā§āĻšā§āϰā§āϤ – ⧍ āύāĻŽā§āĻŦā§°ā§° āĻĒā§ā§°āĻļā§āύā§āϤā§āϤ⧰
1. What is a moment of force ? āĻŦāϞ⧰ āĻŽā§āĻšā§āϰā§āϤ āĻāĻŋ ?
Ans: The moment of a force is the turning effect produced by a force about a point or pivot. āĻāϤā§āϤ⧰: āĻŦāϞ⧰ āĻŽā§āĻšā§āϰā§āϤ āĻšā§āĻā§ āĻā§āύ⧠āĻŦāĻŋāύā§āĻĻā§ āĻŦāĻž pivot-ā§° āĻāĻžā§°āĻŋāĻāĻĢāĻžāϞ⧠āĻŦāϞ⧰ āĻā§ā§°āĻŖā§āϝāĻŧāĻž āĻĒā§ā§°āĻāĻžā§ąāĨ¤
2. Write the formula of moment. āĻŽā§āĻšā§āϰā§āϤ⧰ āϏā§āϤā§ā§° āϞāĻŋāĻāĻžāĨ¤
Ans: Moment = F×d . Moment is equal to force multiplied by perpendicular distance from the pivot.
āĻāϤā§āϤ⧰: āĻŽā§āĻšā§āϰā§āϤ = āĻŦāϞ × pivot-ā§° āĻĒā§°āĻž āϞāĻŽā§āĻŦ āĻĻā§ā§°āϤā§āĻŦāĨ¤
3. State the principle of moments. āĻŽā§āĻšā§āϰā§āϤ⧰ āύā§āϤāĻŋ āĻāϞā§āϞā§āĻ āĻā§°āĻžāĨ¤
Ans: For a body in equilibrium, clockwise moments are equal to anticlockwise moments. āĻāϤā§āϤ⧰: āϏāĻŽāϤāĻžāϤ āĻĨāĻāĻž āĻŦāϏā§āϤā§ā§° āĻā§āώā§āϤā§ā§°āϤ clockwise āĻŽā§āĻšā§āϰā§āϤ āĻā§°ā§ anticlockwise āĻŽā§āĻšā§āϰā§āϤ āϏāĻŽāĻžāύ āĻšāϝāĻŧāĨ¤
4. What is pivot ? Pivot āĻāĻŋ ?
Ans: Pivot is the fixed point about which a body turns. āĻāϤā§āϤ⧰: Pivot āĻšā§āĻā§ āϏā§āĻ āϏā§āĻĨāĻŋā§° āĻŦāĻŋāύā§āĻĻā§ āϝāĻžā§° āĻāĻžā§°āĻŋāĻāĻĢāĻžāϞ⧠āĻŦāϏā§āϤ⧠āĻā§ā§°ā§āĨ¤
5. Name one application of moments. āĻŽā§āĻšā§āϰā§āϤ⧰ āĻāĻāĻž āĻŦā§āĻ¯ā§ąāĻšāĻžā§° āϞāĻŋāĻāĻžāĨ¤
Ans: Seesaw works on the principle of moments. āĻāϤā§āϤ⧰: Seesaw-āĻ āĻŽā§āĻšā§āϰā§āϤ⧰ āύā§āϤāĻŋāϤ āĻāĻžāĻŽ āĻā§°ā§āĨ¤
Moments – 5 Marks Questions with Answers : āĻŽā§āĻšā§āϰā§āϤ – ā§Ģ āύāĻŽā§āĻŦā§°ā§° āĻĒā§ā§°āĻļā§āύā§āϤā§āϤ⧰
1. Define moment of force and write its formula. āĻŦāϞ⧰ āĻŽā§āĻšā§āϰā§āϤ⧰ āϏāĻāĻā§āĻāĻž āĻĻāĻŋāϝāĻŧāĻž āĻā§°ā§ āϏā§āϤā§ā§° āϞāĻŋāĻāĻžāĨ¤
Ans: The moment of force is the turning effect produced by a force about a point or pivot.
Formula: Moment = F × d
Where: F = Force, d = Perpendicular distance from pivot
āĻāϤā§āϤ⧰: āĻŦāϞ⧰ āĻŽā§āĻšā§āϰā§āϤ āĻšā§āĻā§ āĻā§āύ⧠pivot-ā§° āĻāĻžā§°āĻŋāĻāĻĢāĻžāϞ⧠āĻŦāϞ⧰ āĻā§ā§°āĻŖā§āϝāĻŧāĻž āĻĒā§ā§°āĻāĻžā§ąāĨ¤
āϝ’āϤ, F = āĻŦāϞ, d = pivot-ā§° āĻĒā§°āĻž āϞāĻŽā§āĻŦ āĻĻā§ā§°āϤā§āĻŦ
2. Explain the principle of moments with an example. āĻāĻĻāĻžāĻšā§°āĻŖāϏāĻš āĻŽā§āĻšā§āϰā§āϤ⧰ āύā§āϤāĻŋ āĻŦā§āϝāĻžāĻā§āϝāĻž āĻā§°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.
āĻāϤā§āϤ⧰: āĻŽā§āĻšā§āϰā§āϤ⧰ āύā§āϤāĻŋ āĻ āύā§āϏ⧰āĻŋ āϏāĻŽāϤāĻžāϤ āĻĨāĻāĻž āĻŦāϏā§āϤā§ā§° āĻā§āώā§āϤā§ā§°āϤ clockwise āĻā§°ā§ anticlockwise āĻŽā§āĻšā§āϰā§āϤ āϏāĻŽāĻžāύ āĻšāϝāĻŧāĨ¤ āĻāĻĻāĻžāĻšā§°āĻŖāϏā§āĻŦā§°ā§āĻĒā§, seesaw-ā§° āĻĻā§āϝāĻŧā§āĻĢāĻžāϞ⧰ āĻā§ā§°āĻŖā§āϝāĻŧāĻž āĻĒā§ā§°āĻāĻžā§ą āϏāĻŽāĻžāύ āĻšāϞ⧠āĻ āϏāĻŽāϤāĻžāϤ āĻĨāĻžāĻā§āĨ¤
3. What factors affect the moment of force ? āĻŦāϞ⧰ āĻŽā§āĻšā§āϰā§āϤ āĻā§āύ āĻā§āύ āĻāĻžā§°āĻā§ āĻĒā§ā§°āĻāĻžā§ąāĻŋāϤ āĻā§°ā§ ?
Ans: Moment of force depends on: i. Magnitude of force ii. Perpendicular distance from pivot
āĻāϤā§āϤ⧰: āĻŦāϞ⧰ āĻŽā§āĻšā§āϰā§āϤ āύāĻŋā§°ā§āĻā§° āĻā§°ā§: ā§§āĨ¤ āĻŦāϞ⧰ āĻŽāĻžāύ ⧍āĨ¤ pivot-ā§° āĻĒā§°āĻž āϞāĻŽā§āĻŦ āĻĻā§ā§°āϤā§āĻŦ
4. Mention two applications of moments. āĻŽā§āĻšā§āϰā§āϤ⧰ āĻĻā§āĻāĻž āĻŦā§āĻ¯ā§ąāĻšāĻžā§° āĻāϞā§āϞā§āĻ āĻā§°āĻžāĨ¤
Ans: i. Seesaw ii. Spanner
5. Why is a long spanner easier to use than a short spanner ? āĻĻā§āĻāϞ spanner āĻŦā§āĻ¯ā§ąāĻšāĻžā§° āĻā§°āĻž āϏ⧰⧠spanner-āϤāĻā§ āĻāĻŋāϝāĻŧ āϏāĻšāĻ ?
Ans: A long spanner produces greater moment because the perpendicular distance from the pivot is larger.
āĻāϤā§āϤ⧰: āĻĻā§āĻāϞ spanner-āϤ pivot-ā§° āĻĒā§°āĻž āĻĻā§ā§°āϤā§āĻŦ āĻŦā§āĻāĻŋ āĻšāϝāĻŧ, āϏā§āϝāĻŧā§āĻšā§ āĻ āϧāĻŋāĻ āĻŽā§āĻšā§āϰā§āϤ āĻā§āĻĒāύā§āύ āĻšāϝāĻŧ āĻā§°ā§ āĻŦā§āĻ¯ā§ąāĻšāĻžā§° āϏāĻšāĻ āĻšāϝāĻŧāĨ¤