Chapter 9

NCERT
Class 9
Science
Solutions
15. A stone is thrown vertically upward with an initial velocity of 40 m/s. Taking g = 10 m/s2 find the maximum height reached by the stone. What is the net displacement and the total distance covered by the stone ?

Question:

A stone is thrown vertically upward with an initial velocity of 40 m/s. Taking g = 10 m/s2 find the maximum height reached by the stone. What is the net displacement and the total distance covered by the stone ?

Answer:

from the question, u = 40 m/s    g = 10 m/s2     h = ?,     v = 0,     s = ?

(i) from the formula, v2 = u2 – 2gh

0 = (40)2 – 2 × 10 × h

20h = 1600

h = 1600/20

h = 80m

(ii) Net displacement = 0 (Because the stone returns back to the surface after reaching the maximum height.

(iii) Total distance covered by the stone = 80 m + 80 m

                                                                   = 160m

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