Question

A ball is thrown vertically up words & it reaches a height of 90 m. find the velocity with which it was thrown?
......class 11th physics......​

Answer 1

Answer:

the equation of motion v²-u² = 2as

At the peak of the ball’s flight, v=0

so u² = -2as

u² = -2 x -9.8 x 90=1764

u = √ 1764 = 42 m/s

Explanation:

Answer 2

The ball thrown with a speed of 42 m/s.

Explanation:

Let u is the initial speed of the ball. It reaches to a height of 90 m. At this height, its final velocity is equal to 0. We need to find the velocity with which it was thrown. It is given by using third equation of motion as :

$v^2-u^2=2ah$

a = -g

$u=\sqrt{2gh}$

$u=\sqrt{2\times 9.8\times 90}$

u = 42 m/s

So, the ball thrown with a speed of 42 m/s. Hence, this is the required solution.

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Equation of kinematics

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