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Karnataka Board PUCPUC Science Class 11

The bob A of a pendulum released from horizontal to the vertical hits another bob B of the same mass at rest on a table as shown in figure.

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Question

The bob A of a pendulum released from horizontal to the vertical hits another bob B of the same mass at rest on a table as shown in figure.


If the length of the pendulum is 1 m, calculate

  1. the height to which bob A will rise after collision.
  2. the speed with which bob B starts moving. Neglect the size of the bobs and assume the collision to be elastic.
Short/Brief Note
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Solution

a. Two balls have the same mass and the collision between them is elastic, therefore, ball A transfers its entire linear momentum to ball 8. Hence, ball A will come to rest after the collision and does not rise at all.

b. Speed with which bob B starts moving

= Speed with which bob A hits bob B

= `sqrt(2gh)`

= `sqrt(2 xx 9.8 xx 1)`

= `sqrt(19.6)`

= 4.42 m/s

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Chapter 6: Work, Energy and Power - Exercises [Page 47]

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NCERT Exemplar Physics [English] Class 11
Chapter 6 Work, Energy and Power
Exercises | Q 6.37 | Page 47

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