Department of Pre-University Education, KarnatakaPUC Karnataka Science Class 11

# 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 Sitting at a Height of 12.1 M. at a Particular Instant the Bird Drops a Berry. - Physics

Short Note
Sum

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 sitting 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 his uniform?

#### Solution

Speed of the NCC cadets = 6 km/h = 1.66 m/s
Distance of the bird from the ground, s = 12.1 m
Initial velocity of the berry dropped by the bird, u = 0
Acceleration due to gravity, a = g = 9.8 m/s2
Using the equation of motion, we can find the time taken t by the berry to reach the ground.
Thus, we have:

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

$\Rightarrow 12 . 1 = 0 + \frac{1}{2} \times 9 . 8 t^2$

$\Rightarrow t^2 = \frac{12 . 1}{4 . 9} = 2 . 46$

$\Rightarrow t = 1 . 57 s$

Distance moved by the cadets = v × t = 1.57 × 1.66 = 2.6 m
Therefore, the cadet who is 2.6 m away from tree will receive the berry on his uniform.

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#### APPEARS IN

HC Verma Class 11, 12 Concepts of Physics 1
Chapter 3 Rest and Motion: Kinematics
Q 28 | Page 52