Question

A mango in a tree is located at a horizontal? and vertical distance of $30$ m and $40$ m, respectively, from the point of projection of a stone. Find the minimum speed of the stone so as to hit the mango.

• A. $u>30m{s}^{-1}$
• B. $u<30m{s}^{-1}$
• C. $u=50m{s}^{-1}$
• D. $u=40m{s}^{-1}$

Answer 1

The correct option is B $u<30m{s}^{-1}$

R.E.F image

$h=\frac{u^{2}si{n}^2\theta }{2g}$

$40=\frac{u^{2}si{n}^2\theta }{2g}$

$80g=u^{2}si{n}^2\theta$

For min $u,\theta =$

$\Rightarrow 80g=u^2$

$u^2=\sqrt{80g}$

$\therefore 4<30m/s$