SELECT * FROM question_mgmt as q WHERE id=4121 AND status=1 SELECT id,question_no,question,chapter FROM question_mgmt as q WHERE courseId=8 AND subId=16 AND chapterId=187 and ex_no='6' AND status=1 ORDER BY CAST(question_no AS UNSIGNED) CBSE Free NCERT Solution of 9th science Motion a ball is gently dropped from a height of 20 m if

Question:

A ball is gently dropped from a height of 20 m. If its velocity increases uniformly at the rate of 10 m s-2, with what velocity will it strike the ground? After what time will it strike the ground?

Answer:

Distance covered by the ball, s = 20 m

Acceleration, a = 10 m/s2

Initially, velocity, u = 0 

Final velocity, v = ?

Time, t = ?

According to the third equation of motion:

v2 = u2 + 2 as

v2 = 0 + 2 (10) (20)

v = 20 m/s

According to the first equation of motion:

v = u + at

20 = 0 + 10 (t)

t = 2 s

Hence, time taken to reach at the ground is 2 seconds.


SELECT ex_no,question,question_no,id,chapter FROM question_mgmt as q WHERE courseId='8' AND subId='16' AND ex_no!=0 AND status=1 and id!=4121 ORDER BY views desc, last_viewed_on desc limit 0,10
SELECT ex_no,question,question_no,id,chapter FROM question_mgmt as q WHERE courseId='8' AND subId='16' AND ex_no!=0 AND status=1 and id!=4121 ORDER BY last_viewed_on desc limit 0,10

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  • 4 months ago

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  • Answered by Ekta Mehta
  • 4 months ago

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  • Answered by Ekta Mehta
  • 4 months ago

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