Question

An NCC parade is going at a uniform speed of 6 km/h through a place under a berry tree on which a bird is siting at a height of 12.1 m. At a particular instant the bird drops a berry. Which cadet (give the distance from the tree at the instant) will receive the berry on this uniform.

Answer 1

Let the true time of fall be 't'

Initial velocity, u = 0

Acceleration = $9.8m/s^2$

Distance, S = 12.1 m

$\therefore S=ut+\frac{1}{2}a{t}^2$

$\Rightarrow 12.1=0+\frac{1}{2}\times 9.8t^2$

$\Rightarrow t^2=0+\frac{12.1}{4.9}=2.46$

$\Rightarrow$ t = 1.57 sec

For cadet velocity = 6 km/hr = 1.66 m\sec

Distance = vt = 1.57 \times 1.66 = 2.6 m

The cadet, 2.6 m away from tree will receive the berry on his uniform.