Question

5.
What is the velocity of the stone when it is 40 m above the ground, while moving upwards?
(A) 50 m/s
(B) 30 m/s
(C) 20 m/s
(D) 2012 m/s​

Answer 1

According to the equation of the motion under gravity

v

2

−u

2

=2gs

u=initial velocity of the stone=40m/s

v= Final velocity of the stone=0m/s

Let h be the maximum height attained by the stone

Therefore,

0

2

−40

2

=2(−10)h

h=(40×40)/20=80

Therefore, total distance covered by the stone during its upward and downward journey=80+80=160m

Net displacement during its upward and downward journey=80+(−80)=0

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