Question 5

A stone is thrown in a 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?

Answer

Initially, velocity of the stone,*u* = 5 m/s

Final velocity, *v* = 0

Acceleration of the stone, *a* = acceleration due to gravity, g = 10 m/s^{2}

Since, u is upward & a is downward, it is a retarded motion.

Acceleration, *a* = −10 m/s^{2}

Let *s* be the maximum height attained by the stone in time *t*.

According to the first equation of motion:

*v* = *u* + *at*

0 = 5 + (−10)* t*

According to the third equation of motion:

*v*^{2} = *u*^{2} + 2 *as*

(0)^{2} = (5)^{2} + 2(−10) s

However , the stone attains a height of 1.25 m in 0.5 s.

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