. A stone is thrown in vertically upward direction with a velocity of


5 m s-1. If the acceleration of the stone during its motion is 10 m s-2 in the downward direction, what will be the height attained by the stone and how much time will it take to reach there?

 

Best Answer

Sol. As the stone is thrown vertically upwards therefore, the acceleration of the stone will be denoted with a negative sign.

So, Acceleration, a = - 10 m/s2

Initial velocity, u = 5 m/s1

Final velocity, v = 0 (As it stops at the top)

And,

Distance travelled, s =?

As, v2 = u2 + 2as

 (0)2 = (5)2 + 2 × (-10) × s

 0 = 25 – 20 s

 20 s = 25

 s =  25/20

 s = 1.25 m

 Therefore, the height attained by the stone will be 1.25 metres

Now, we have to find out the time

As we know that:

v = u + at

0 = 5 + (-10) × t

0 = 5 – 10t

10t = 5

t =  

t = 0.5 s

Therefore, 0.5 seconds will be taken by the stone to reach at the top.

 

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