Question

A stone projected vertically upwards takes 1.5s to reach the highest point . Calculate initial velocity of stone maximum height attined by it

Answer 1

$\huge{\bold{\underline{\underline{....Answer....}}}}$

$\huge{\bold{\underline{Given:-}}}$

t = 1.5 seconds.

g = - 10 m/s².(As it is moving against gravity)

v = 0 m/s.

(At highest point velocity is zero)

$\huge{\bold{\underline{Explanation:-}}}$

Initial velocity:-

Using first kinematics equation,

$\large{\bold{v = u + at}}$

$\large{ 0 = u + ( - 10 \times 1.5)}$

$\large{0 = u - 10 \times 1.5}$

$\large{u = 10 \times 1.5}$

$\huge{\boxed{\boxed{u = 15 \: m/s}}}$

So, the initial velocity of the stone is 15 m/s.

Maximum height:-

From third kinematic equation,

$\large{\bold{v^2 - u^2 = 2as}}$

Substituting the values,

$\large{0 - (15)^2 = 2 \times -10 \times H}$

$\large{- 225 = - 20 \times H}$

$\large{ \cancel{-} 225 = \cancel{-} 20 \times H}$

$\large{225 = 20 \times H}$

$\large{H = \frac{225}{20}}$

$\huge{\boxed{\boxed{H = 11.25 \: meters}}}$

So, the maximum height attained is 11.25 meters.