SELECT * FROM question_mgmt as q WHERE id=4184 AND status=1 SELECT id,question_no,question,chapter FROM question_mgmt as q WHERE courseId=8 AND subId=16 AND chapterId=190 and ex_no='6' AND status=1 ORDER BY CAST(question_no AS UNSIGNED) CBSE Free NCERT Solution of 9th science Gravitation a ball thrown up vertically returns to the thrower

Question:

A ball thrown up vertically returns to the thrower after 6 s. Find
(a) the velocity with which it was thrown up,
(b) the maximum height it reaches, and
(c) its position after 4 s.

Answer:

The ball takes a total of 6 s for its upward and downward journey.

Time taken to reach maximum height = 6 / 2 = 3 s

Hence, it has taken 3 s to attain the maximum height

(a)

Let initial velocity = u m/s

Final velocity of the ball at the maximum height, v = 0 m/s

Acceleration due to gravity, g = −9.8 m s−2

Equation of motion

v = u + gt 

0 = u + (−9.8 × 3)

u = 9.8 × 3 = 29.4 ms−1

Hence, the ball was thrown upwards with a velocity of 29.4 m s−1.

(b)

Let the maximum height attained by the ball = h

Initial velocity during the upward journey, u = 29.4 m/s

Final velocity, v = 0 m/s

Acceleration due to gravity, g = −9.8 m s−2

From the equation of motion,


(c) Ball attains the maximum height after 3 s. After attaining this height, it will start falling downwards.

In this case,

Initial velocity, u = 0 m/s

Position of the ball after 4 s of the throw is given by the distance travelled by it during its downward journey in 4 s − 3 s = 1 s.

Equation of motion, 

s = 0 x 1 + ½ x 9.8 x 12

s = 4.9 m 

Total height = 44.1 m

This means that the ball is 39.2 m (44.1 m − 4.9 m) above the ground after 4 seconds.

 


< Previous Question

Next Question >

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!=4184 ORDER BY views desc, last_viewed_on desc limit 0,10

  • Popular questions of class 9 Science

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!=4184 ORDER BY last_viewed_on desc limit 0,10

  • Recently Viewed Questions of Class 9 Science

Comments

  • Answered by Ekta Mehta
  • 4 months ago

Taking Screenshots on your Samsung Galaxy M31s is very easy and quick.

  • Answered by Ekta Mehta
  • 4 months ago

Taking Screenshots on your Samsung Galaxy M31s is very easy and quick.

  • Answered by Ekta Mehta
  • 4 months ago

Taking Screenshots on your Samsung Galaxy M31s is very easy and quick.

Comment(s) on this Question


NCERT Solutions

Quick Links

Resources

Support