Impulse : āĻ…āĻ­āĻŋāϘāĻžāϤ = Formula & When to Use : āϏ⧂āĻ¤ā§ā§° āφ⧰⧁ āĻŦā§āĻ¯ā§ąāĻšāĻžā§°













Impulse : āĻ…āĻ­āĻŋāϘāĻžāϤ : Impulse is the change in momentum of an object. (āĻ…āĻ­āĻŋāϘāĻžāϤ āĻšā§ˆāϛ⧇ āϕ⧋āύ⧋ āĻŦāĻ¸ā§āϤ⧁⧰ āĻ­ā§°āĻŦ⧇āĻ—ā§° āĻĒā§°āĻŋāĻŦāĻ°ā§āϤāύāĨ¤) When force acts on an object for some time, velocity and momentum change. (āϝ⧇āϤāĻŋāϝāĻŧāĻž āϕ⧋āύ⧋ āĻŦāĻ¸ā§āϤ⧁⧰ āĻ“āĻĒā§°āϤ āĻ•āĻŋāϛ⧁ āϏāĻŽāϝāĻŧ āϧ⧰āĻŋ āĻŦāϞ āĻĒā§ā§°āϝāĻŧā§‹āĻ— āĻšāϝāĻŧ, āϤ⧇āϤāĻŋāϝāĻŧāĻž āĻŦ⧇āĻ— āφ⧰⧁ āĻ­ā§°āĻŦ⧇āĻ— āϏāϞāύāĻŋ āĻšāϝāĻŧāĨ¤)


Formula & When to Use  : āϏ⧂āĻ¤ā§ā§° āφ⧰⧁ āĻŦā§āĻ¯ā§ąāĻšāĻžā§°


Formula / āϏ⧂āĻ¤ā§ā§°: Impulse = F × t



  • Impulse = Force × Time (āĻ…āĻ­āĻŋāϘāĻžāϤ = āĻŦāϞ × āϏāĻŽāϝāĻŧ)

  • Impulse = Change in momentum (āĻ…āĻ­āĻŋāϘāĻžāϤ = āĻ­ā§°āĻŦ⧇āĻ—ā§° āĻĒā§°āĻŋāĻŦāĻ°ā§āϤāύ)



Where / āϝ’āϤ : F = Force / āĻŦāϞ, t = Time / āϏāĻŽāϝāĻŧ

 

 When to Use ? āϕ⧇āϤāĻŋāϝāĻŧāĻž āĻŦā§āĻ¯ā§ąāĻšāĻžā§° āϕ⧰āĻž āĻšāϝāĻŧ ?


1. When force is applied for time (ā§§. āϝ⧇āϤāĻŋāϝāĻŧāĻž āĻ•āĻŋāϛ⧁ āϏāĻŽāϝāĻŧ āϧ⧰āĻŋ āĻŦāϞ āĻĒā§ā§°āϝāĻŧā§‹āĻ— āĻšāϝāĻŧ)


Use impulse formula when force acts for a certain duration.
āϝ⧇āϤāĻŋāϝāĻŧāĻž āϕ⧋āύ⧋ āϏāĻŽāϝāĻŧ āϧ⧰āĻŋ āĻŦāϞ āĻĒā§ā§°āϝāĻŧā§‹āĻ— āĻšāϝāĻŧ āϤ⧇āϤāĻŋāϝāĻŧāĻž āĻ…āĻ­āĻŋāϘāĻžāϤ⧰ āϏ⧂āĻ¤ā§ā§° āĻŦā§āĻ¯ā§ąāĻšāĻžā§° āϕ⧰āĻž āĻšāϝāĻŧāĨ¤


2. When time duration is given (⧍. āϝ⧇āϤāĻŋāϝāĻŧāĻž āϏāĻŽāϝāĻŧ āĻĻāĻŋāϝāĻŧāĻž āĻĨāĻžāϕ⧇)

If force and time are given, impulse can be calculated. āĻŦāϞ āφ⧰⧁ āϏāĻŽāϝāĻŧ āĻĻāĻŋāϝāĻŧāĻž āĻĨāĻžāĻ•āĻŋāϞ⧇ āĻ…āĻ­āĻŋāϘāĻžāϤ āύāĻŋā§°ā§āĻŖāϝāĻŧ āϕ⧰āĻŋāĻŦ āĻĒāĻžā§°āĻŋāĨ¤


3. To find change in momentum (ā§Š. āĻ­ā§°āĻŦ⧇āĻ—ā§° āĻĒā§°āĻŋāĻŦāĻ°ā§āϤāύ āϜāĻžāύāĻŋāĻŦāϞ⧈)

Impulse helps to find change in momentum. (āĻ…āĻ­āĻŋāϘāĻžāϤ⧇ āĻ­ā§°āĻŦ⧇āĻ—ā§° āĻĒā§°āĻŋāĻŦāĻ°ā§āϤāύ āϜāĻžāύāĻŋāĻŦāϞ⧈ āϏāĻšāĻžāϝāĻŧ āϕ⧰⧇āĨ¤)


Important Concep  (āϗ⧁⧰⧁āĻ¤ā§āĻŦāĻĒā§‚āĻ°ā§āĻŖ āϧāĻžā§°āĻŖāĻž)



  • More force → More impulse (āĻ…āϧāĻŋāĻ• āĻŦāϞ → āĻ…āϧāĻŋāĻ• āĻ…āĻ­āĻŋāϘāĻžāϤ)

  • More time → More impulse (āĻ…āϧāĻŋāĻ• āϏāĻŽāϝāĻŧ → āĻ…āϧāĻŋāĻ• āĻ…āĻ­āĻŋāϘāĻžāϤ)

  • Force changes velocity (āĻŦāϞ⧇ āĻŦ⧇āĻ— āϏāϞāύāĻŋ āϕ⧰⧇)

  • Velocity change → Momentum change (āĻŦ⧇āĻ— āϏāϞāύāĻŋ → āĻ­ā§°āĻŦ⧇āĻ— āϏāϞāύāĻŋ)


SI Unit / SI āĻāĻ•āĻ• : Impulse unit = N·s = kg·m/s (āĻ…āĻ­āĻŋāϘāĻžāϤ⧰ āĻāĻ•āĻ• = N·s = kg·m/s)


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Impulse MCQ : āĻ…āĻ­āĻŋāϘāĻžāϤ MCQ


1. What is impulse ? āĻ…āĻ­āĻŋāϘāĻžāϤ āĻ•āĻŋ ?













A) Change in force  B) Change in momentum  C) Change in mass  D) Change in density


Ans: B) Change in momentum


Explanation: Impulse is the change in momentum of an object. āĻ…āĻ­āĻŋāϘāĻžāϤ āĻšā§ˆāϛ⧇ āĻŦāĻ¸ā§āϤ⧁⧰ āĻ­ā§°āĻŦ⧇āĻ—ā§° āĻĒā§°āĻŋāĻŦāĻ°ā§āϤāύāĨ¤


2. The formula of impulse is: āĻ…āĻ­āĻŋāϘāĻžāϤ⧰ āϏ⧂āĻ¤ā§ā§° āϕ⧋āύāĻŸā§‹ ?

A) P = mv  B) F = ma  C) Impulse = F × t  D) W = mg


Ans: C) Impulse = F × t


Explanation: Impulse = F × t, Impulse equals force multiplied by time. (āĻ…āĻ­āĻŋāϘāĻžāϤ = āĻŦāϞ × āϏāĻŽāϝāĻŧāĨ¤)


3. Impulse depends on: āĻ…āĻ­āĻŋāϘāĻžāϤ āĻ•āĻŋāĻšā§° āĻ“āĻĒā§°āϤ āύāĻŋā§°ā§āĻ­ā§° āϕ⧰⧇ ?

A) Mass and speed  B) Force and time  C) Pressure and heat  D) Density and volume


Ans: B) Force and time


Explanation: More force or more time gives more impulse. āĻ…āϧāĻŋāĻ• āĻŦāϞ āĻŦāĻž āĻ…āϧāĻŋāĻ• āϏāĻŽāϝāĻŧ⧇ āĻ…āϧāĻŋāĻ• āĻ…āĻ­āĻŋāϘāĻžāϤ āĻĻāĻŋāϝāĻŧ⧇āĨ¤)


4. SI unit of impulse is: āĻ…āĻ­āĻŋāϘāĻžāϤ⧰ SI āĻāĻ•āĻ• āĻ•āĻŋ ?

A) Joule  B) Watt  C) Newton-second  D) Pascal


Ans: C) Newton-second


Explanation: SI unit of impulse = N·s. (āĻ…āĻ­āĻŋāϘāĻžāϤ⧰ SI āĻāĻ•āĻ• = N·s)


5. Impulse is equal to: āĻ…āĻ­āĻŋāϘāĻžāϤ āĻ•āĻŋāĻšā§° āϏāĻŽāĻžāύ ?

A) Velocity  B) Mass  C) Change in momentum  D) Acceleration


Ans: C) Change in momentum


Explanation: Impulse and change in momentum are equal. (āĻ…āĻ­āĻŋāϘāĻžāϤ āφ⧰⧁ āĻ­ā§°āĻŦ⧇āĻ—ā§° āĻĒā§°āĻŋāĻŦāĻ°ā§āϤāύ āϏāĻŽāĻžāύāĨ¤)


6. If time increases, impulse will: āϏāĻŽāϝāĻŧ āĻŦ⧃āĻĻā§āϧāĻŋ āĻĒāĻžāϞ⧇ āĻ…āĻ­āĻŋāϘāĻžāϤ -

A) Decrease  B) Increase  C) Become zero  D) Remain same


Ans: B) Increase


Explanation: Impulse is directly proportional to time. (āĻ…āĻ­āĻŋāϘāĻžāϤ āϏāĻŽāϝāĻŧā§° āϏ⧈āϤ⧇ āϏāĻŽāĻžāύ⧁āĻĒāĻžāϤāĻŋāĻ•āĨ¤)


7. A large force acting for short time produces: (āĻ…āĻ˛ā§āĻĒ āϏāĻŽāϝāĻŧā§° āĻŦāĻžāĻŦ⧇ āĻŦ⧃āĻšā§Ž āĻŦāϞ⧇ āĻ•āĻŋ āĻ‰ā§ŽāĻĒāĻ¨ā§āύ āϕ⧰⧇ ?)

A) Small impulse  B) Large impulse  C) Zero impulse  D) Constant impulse


Ans: B) Large impulse


Explanation: Large force can produce large impulse even in short time. (āĻŦ⧃āĻšā§Ž āĻŦāϞ⧇ āĻ•āĻŽ āϏāĻŽāϝāĻŧāϤ⧋ āĻ…āϧāĻŋāĻ• āĻ…āĻ­āĻŋāϘāĻžāϤ āĻ‰ā§ŽāĻĒāĻ¨ā§āύ āϕ⧰āĻŋāĻŦ āĻĒāĻžā§°ā§‡āĨ¤)


8. Catching a ball with soft hands increases: (āύāϰāĻŽ āĻšāĻžāϤ⧇⧰⧇ āĻŦāϞ āϧ⧰āĻŋāϞ⧇ āĻ•āĻŋ āĻŦ⧃āĻĻā§āϧāĻŋ āĻĒāĻžāϝāĻŧ ?)

A) Force  B) Mass  C) Time of contact  D) Speed


Ans: C) Time of contact


Explanation: Soft hands increase contact time and reduce force. (āύāϰāĻŽ āĻšāĻžāϤ⧇ āϏāĻ‚āĻ¸ā§āĻĒāĻ°ā§āĻļā§° āϏāĻŽāϝāĻŧ āĻŦ⧃āĻĻā§āϧāĻŋ āϕ⧰⧇ āφ⧰⧁ āĻŦāϞ āĻ•āĻŽāĻžāϝāĻŧāĨ¤)


9. Which quantity changes due to impulse ? āĻ…āĻ­āĻŋāϘāĻžāϤ⧰ āĻŦāĻžāĻŦ⧇ āϕ⧋āύ ā§°āĻžāĻļāĻŋ āϏāϞāύāĻŋ āĻšāϝāĻŧ ?

A) Density  B) Volume  C) Momentum  D) Shape


Ans: C) Momentum


Explanation: Impulse changes momentum. (āĻ…āĻ­āĻŋāϘāĻžāϤ⧇ āĻ­ā§°āĻŦ⧇āĻ— āϏāϞāύāĻŋ āϕ⧰⧇āĨ¤)


10. Find impulse when force = 8 N and time = 2 s. (āĻŦāϞ = 8 N āφ⧰⧁ āϏāĻŽāϝāĻŧ = 2 s āĻšāϞ⧇ āĻ…āĻ­āĻŋāϘāĻžāϤ āύāĻŋā§°ā§āĻŖāϝāĻŧ āϕ⧰āĻžāĨ¤)

A) 10 N·s  B) 12 N·s  C) 16 N·s  D) 18 N·s


Ans: C) 16 N·s


Explanation: Impulse(āĻ…āĻ­āĻŋāϘāĻžāϤ)  = F × t = 8 × 2 = 16 N·s


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2 Marks Questions (PYQ) : ⧍ āύāĻŽā§āĻŦā§°ā§° āĻĒā§āϰāĻļā§āύ (PYQ)


1. Define impulse. āĻ…āĻ­āĻŋāϘāĻžāϤ⧰ āϏāĻ‚āĻœā§āĻžāĻž āϞāĻŋāĻ–āĻžāĨ¤

Ans: Impulse is the change in momentum of an object. (āĻ…āĻ­āĻŋāϘāĻžāϤ āĻšā§ˆāϛ⧇ āϕ⧋āύ⧋ āĻŦāĻ¸ā§āϤ⧁⧰ āĻ­ā§°āĻŦ⧇āĻ—ā§° āĻĒā§°āĻŋāĻŦāĻ°ā§āϤāύāĨ¤)


2. Write the formula of impulse. āĻ…āĻ­āĻŋāϘāĻžāϤ⧰ āϏ⧂āĻ¤ā§ā§° āϞāĻŋāĻ–āĻžāĨ¤

Ans: Impulse = F×t {Impulse = Force × Time (āĻ…āĻ­āĻŋāϘāĻžāϤ = āĻŦāϞ × āϏāĻŽāϝāĻŧ)}


3. Write the SI unit of impulse. āĻ…āĻ­āĻŋāϘāĻžāϤ⧰ SI āĻāĻ•āĻ• āϞāĻŋāĻ–āĻžāĨ¤

Ans: SI unit of impulse = Newton-second (N·s) (āĻ…āĻ­āĻŋāϘāĻžāϤ⧰ SI āĻāĻ•āĻ• = āύāĻŋāωāϟāύ-āϛ⧇āϕ⧇āĻŖā§āĻĄ (N·s))


4. On which factors does impulse depend ? āĻ…āĻ­āĻŋāϘāĻžāϤ āĻ•āĻŋāĻšā§° āĻ“āĻĒā§°āϤ āύāĻŋā§°ā§āĻ­ā§° āϕ⧰⧇ ?

Ans: Impulse depends on force and time. (āĻ…āĻ­āĻŋāϘāĻžāϤ āĻŦāϞ āφ⧰⧁ āϏāĻŽāϝāĻŧā§° āĻ“āĻĒā§°āϤ āύāĻŋā§°ā§āĻ­ā§° āϕ⧰⧇āĨ¤)


5. What happens to impulse when force increases ? āĻŦāϞ āĻŦ⧃āĻĻā§āϧāĻŋ āĻĒāĻžāϞ⧇ āĻ…āĻ­āĻŋāϘāĻžāϤ⧰ āĻ•āĻŋ āĻšāϝāĻŧ ?

Ans: Impulse increases with increase in force. (āĻŦāϞ āĻŦ⧃āĻĻā§āϧāĻŋ āĻĒāĻžāϞ⧇ āĻ…āĻ­āĻŋāϘāĻžāϤ⧋ āĻŦ⧃āĻĻā§āϧāĻŋ āĻĒāĻžāϝāĻŧāĨ¤)


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5 Marks Questions (PYQ) : ā§Ģ āύāĻŽā§āĻŦā§°ā§° āĻĒā§āϰāĻļā§āύ (PYQ)


1. Explain impulse with formula and SI unit. āĻ…āĻ­āĻŋāϘāĻžāϤ āϏ⧂āĻ¤ā§ā§° āφ⧰⧁ SI āĻāĻ•āĻ•āϏāĻš āĻŦā§āϝāĻžāĻ–ā§āϝāĻž āϕ⧰āĻžāĨ¤


Ans: Impulse is the change in momentum of an object. When a force acts on a body for a certain time, the momentum changes. (āĻ…āĻ­āĻŋāϘāĻžāϤ āĻšā§ˆāϛ⧇ āĻŦāĻ¸ā§āϤ⧁⧰ āĻ­ā§°āĻŦ⧇āĻ—ā§° āĻĒā§°āĻŋāĻŦāĻ°ā§āϤāύāĨ¤ āĻ•āĻŋāϛ⧁ āϏāĻŽāϝāĻŧ āϧ⧰āĻŋ āĻŦāϞ āĻĒā§ā§°āϝāĻŧā§‹āĻ— āϕ⧰āĻŋāϞ⧇ āĻ­ā§°āĻŦ⧇āĻ— āϏāϞāύāĻŋ āĻšāϝāĻŧāĨ¤)













Impulse = F × t


Where, F = Force , t = Time


2. Calculate impulse when a force of 12 N acts for 4 s. (12 N āĻŦāϞ⧇ 4 s āϏāĻŽāϝāĻŧ āϧ⧰āĻŋ āĻ•ā§āϰāĻŋāϝāĻŧāĻž āϕ⧰āĻŋāϞ⧇ āĻ…āĻ­āĻŋāϘāĻžāϤ āύāĻŋā§°ā§āĻŖāϝāĻŧ āϕ⧰āĻžāĨ¤)

Ans:


Given / āĻĻāĻŋāϝāĻŧāĻž āφāϛ⧇: Force = 12 N, Time = 4 s


Impulse = F × t  = 12 × 4 = 48 N·s


Impulse = 48 N·s.


3. Explain relation between impulse and momentum. (āĻ…āĻ­āĻŋāϘāĻžāϤ āφ⧰⧁ āĻ­ā§°āĻŦ⧇āĻ—ā§° āϏāĻŽā§āĻĒāĻ°ā§āĻ• āĻŦā§āϝāĻžāĻ–ā§āϝāĻž āϕ⧰āĻžāĨ¤)

Ans: Impulse is equal to the change in momentum of an object. When force acts for some time, momentum changes. āĻ…āĻ­āĻŋāϘāĻžāϤ āĻŦāĻ¸ā§āϤ⧁⧰ āĻ­ā§°āĻŦ⧇āĻ—ā§° āĻĒā§°āĻŋāĻŦāĻ°ā§āϤāύ⧰ āϏāĻŽāĻžāύāĨ¤ āĻ•āĻŋāϛ⧁ āϏāĻŽāϝāĻŧ āϧ⧰āĻŋ āĻŦāϞ āĻĒā§ā§°āϝāĻŧā§‹āϗ⧇ āĻ­ā§°āĻŦ⧇āĻ— āϏāϞāύāĻŋ āϕ⧰⧇āĨ¤


4. Why do airbags reduce injury during accidents ? āĻĻā§ā§°ā§āϘāϟāύāĻžāϤ āĻāϝāĻŧāĻžā§°āĻŦ⧇āϗ⧇ āφāϘāĻžāϤ āĻ•āĻŋāϝāĻŧ āĻ•āĻŽāĻžāϝāĻŧ ?

Ans: Airbags increase the time of contact during collision. Increased time reduces force and injury. āĻāϝāĻŧāĻžā§°āĻŦ⧇āϗ⧇ āϏāĻ‚āϘāĻ°ā§āώ⧰ āϏāĻŽāϝāĻŧ āĻŦ⧃āĻĻā§āϧāĻŋ āϕ⧰⧇āĨ¤ āϏāĻŽāϝāĻŧ āĻŦ⧃āĻĻā§āϧāĻŋ āĻĒāĻžāϞ⧇ āĻŦāϞ āĻ•āĻŽā§‡ āφ⧰⧁ āφāϘāĻžāϤ⧋ āĻ•āĻŽ āĻšāϝāĻŧāĨ¤


5. A force of 20 N acts on a body for 3 s. Find the impulse. (20 N āĻŦāϞ⧇ 3 s āϏāĻŽāϝāĻŧ āϧ⧰āĻŋ āĻŦāĻ¸ā§āϤ⧁⧰ āĻ“āĻĒā§°āϤ āĻ•ā§āϰāĻŋāϝāĻŧāĻž āϕ⧰āĻŋāϛ⧇āĨ¤ āĻ…āĻ­āĻŋāϘāĻžāϤ āύāĻŋā§°ā§āĻŖāϝāĻŧ āϕ⧰āĻžāĨ¤)

Ans:


Given / āĻĻāĻŋāϝāĻŧāĻž āφāϛ⧇: Force = 20 N, Time = 3 s


Impulse = F × t  = 20 × 3 = 60 N·s


Therefore, impulse = 60 N·s.