Same Speed, Different Velocity : āĻāϕ⧇ āĻĻā§ā§°ā§āϤāĻŋ, āĻ•āĻŋāĻ¨ā§āϤ⧁ āĻŦ⧇āϞ⧇āĻ— āĻŦ⧇āĻ—


Same Speed, Different Velocity : How ? : āĻāϕ⧇ āĻĻā§ā§°ā§āϤāĻŋ, āĻ•āĻŋāĻ¨ā§āϤ⧁ āĻŦ⧇āϞ⧇āĻ— āĻŦ⧇āĻ—


Both runners have speed = 5 m/s (āĻĻ⧁āϝāĻŧā§‹āϜāύ āĻĻ⧌⧰āĻŦāĻŋāĻĻā§° āĻĻā§ā§°ā§āϤāĻŋ = ā§Ģ āĻŽāĻŋ/āϛ⧇)


Runner A / āĻĻ⧌⧰āĻŦāĻŋāĻĻ A


Straight path → Large displacement (āϏ⧋āϜāĻž āĻĒāĻĨ → āĻ…āϧāĻŋāĻ• āĻ¸ā§āĻĨāĻžāύāĻžāĻ¨ā§āϤ⧰ (Displacement))


5 m/s → → → Since direction remains almost the same, Velocity is larger in that direction. (āϝāĻŋāĻšā§‡āϤ⧁ āĻĻāĻŋāĻļ āĻĒā§ā§°āĻžāϝāĻŧ āĻāϕ⧇āχ āĻĨāĻžāϕ⧇, āϏ⧇āϝāĻŧ⧇ āϏ⧇āχ āĻĻāĻŋāĻļāϤ āĻŦ⧇āĻ— āĻ…āϧāĻŋāĻ• āĻšāϝāĻŧāĨ¤)



Runner B / āĻĻ⧌⧰āĻŦāĻŋāĻĻ B


Circular path → Direction keeps changing (āĻŦ⧃āĻ¤ā§āϤāĻžāĻ•āĻžā§° āĻĒāĻĨ → āĻĻāĻŋāĻļ āϏāĻĻāĻžāϝāĻŧ āϏāϞāύāĻŋ āĻšā§ˆ āĻĨāĻžāϕ⧇)


5 m/s âŸŗ


Smaller displacement (āĻ•āĻŽ āĻ¸ā§āĻĨāĻžāύāĻžāĻ¨ā§āϤ⧰)


If one full circle is completed: (āϝāĻĻāĻŋ āĻāϟāĻž āϏāĻŽā§āĻĒā§‚ā§°ā§āĻŖ āĻŦ⧃āĻ¤ā§āϤ āϏāĻŽā§āĻĒāĻ¨ā§āύ āĻšāϝāĻŧ -)


Displacement = 0 (āĻ¸ā§āĻĨāĻžāύāĻžāĻ¨ā§āϤ⧰ = ā§Ļ)


Therefore, velocity can become zero. (āϏ⧇āϝāĻŧ⧇, āĻŦ⧇āĻ— āĻļā§‚āĻ¨ā§āϝ āĻš’āĻŦ āĻĒāĻžā§°ā§‡āĨ¤)


Idea / āϧāĻžā§°āĻŖāĻž


Even if two runners move at the same speed, their velocities can be different if their directions are different. (āϝāĻĻāĻŋāĻ“ āĻĻ⧁āϝāĻŧā§‹āϜāύ āĻĻ⧌⧰āĻŦāĻŋāĻĻ āĻāϕ⧇ āĻĻā§ā§°ā§āϤāĻŋ⧰⧇ āϚāϞ⧇, āĻĻāĻŋāĻļ āĻŦ⧇āϞ⧇āĻ— āĻš’āϞ⧇ āϏāĻŋāĻšāρāϤ⧰ āĻŦ⧇āĻ— āĻŦ⧇āϞ⧇āĻ— āĻš’āĻŦ āĻĒāĻžā§°ā§‡āĨ¤)


Important Note / āϗ⧁⧰⧁āĻ¤ā§āĻŦāĻĒā§‚āĻ°ā§āĻŖ āĻŸā§‹āĻ•āĻž


Speed depends only on magnitude. (āĻĻā§ā§°ā§āϤāĻŋ āĻ•ā§‡ā§ąāϞ āĻŽāĻžāύ⧰ āĻ“āĻĒā§°āϤ āύāĻŋā§°ā§āĻ­ā§° āϕ⧰⧇āĨ¤)


Velocity depends on magnitude and direction. (āĻŦ⧇āĻ— āĻŽāĻžāύ āφ⧰⧁ āĻĻāĻŋāĻļ āĻĻ⧁āϝāĻŧā§‹āϟāĻžā§° āĻ“āĻĒā§°āϤ āύāĻŋā§°ā§āĻ­ā§° āϕ⧰⧇āĨ¤)


Exam Tip / āĻĒā§°ā§€āĻ•ā§āώāĻžā§° āϟāĻŋāĻĒāĻ›



  • Speed is a scalar quantity (āĻĻā§ā§°ā§āϤāĻŋ āĻāϟāĻž Scalar QuantityāĨ¤)

  • Velocity is a vector quantit (āĻŦ⧇āĻ— āĻāϟāĻž Vector QuantityāĨ¤)


Comparison / āϤ⧁āϞāύāĻž








Speed (āĻĻā§ā§°ā§āϤāĻŋ)



  • Only magnitude (āĻ•ā§‡ā§ąāϞ āĻŽāĻžāύ āĻĨāĻžāϕ⧇)

  • Scalar quantity (āχ āĻāϟāĻž Scalar Quantity)

  • Distance is used (āĻĻā§‚ā§°āĻ¤ā§āĻŦ āĻŦā§āĻ¯ā§ąāĻšāĻžā§° āϕ⧰āĻž āĻšāϝāĻŧ)

  • Direction is not needed (āĻĻāĻŋāĻļā§° āĻĒā§ā§°āϝāĻŧā§‹āϜāύ āύāĻšāϝāĻŧ)


Velocity (āĻŦ⧇āĻ—)

  • Magnitude + direction (āĻŽāĻžāύ + āĻĻāĻŋāĻļ āĻĻ⧁āϝāĻŧā§‹āϟāĻž āĻĨāĻžāϕ⧇)

  • Vector quantity (āχ āĻāϟāĻž Vector Quantity)

  • Displacement is used (āĻ¸ā§āĻĨāĻžāύāĻžāĻ¨ā§āϤ⧰ āĻŦā§āĻ¯ā§ąāĻšāĻžā§° āϕ⧰āĻž āĻšāϝāĻŧ)

  • Direction is needed (āĻĻāĻŋāĻļā§° āĻĒā§ā§°āϝāĻŧā§‹āϜāύ āĻšāϝāĻŧ)


Question / āĻĒā§ā§°āĻļā§āύ: A runner completes one full circular track and comes back to the starting point. What is the displacement ? āĻāϜāύ āĻĻ⧌⧰āĻŦāĻŋāĻĻ⧇ āĻāϟāĻž āϏāĻŽā§āĻĒā§‚ā§°ā§āĻŖ āĻŦ⧃āĻ¤ā§āϤāĻžāĻ•āĻžā§° āĻĒāĻĨ āĻļ⧇āώ āϕ⧰āĻŋ āĻĒ⧁āύ⧰ āφ⧰āĻŽā§āĻ­āĻŖāĻŋ āĻ¸ā§āĻĨāĻžāύāϞ⧈ āφāĻšāĻŋāϞāĨ¤āĻ¸ā§āĻĨāĻžāύāĻžāĻ¨ā§āϤ⧰ āĻ•āĻŋāĻŽāĻžāύ ?


Ans / āωāĻ¤ā§āϤ⧰: 0 m, Because : Initial position = Final position (āφ⧰āĻŽā§āĻ­āĻŖāĻŋ āĻ¸ā§āĻĨāĻžāύ = āĻļ⧇āώ āĻ¸ā§āĻĨāĻžāύ)