Question

An aeroplane is flying in a horizontal direction with a velocity u and at a height of 2000m. When it is vertically below a point A on the ground a food packet is released from it . The packet strikes the ground at point B. If ab=3km and g=10 then the value of u is.

Answer 1

In vertical direction,

Initial velocity = 0 m/s

Height = 2000 m

Acceleration = 10 m/s^2

Let the time taken in reaching ground be t.

Now,

$H = v_i \times t + \frac{1}{2 } \times a \times t^2$

$2000 = 0 +\frac{1}{2} \times 10 \times t^2$

$t = \sqrt{\frac{2 \times 2000}{10} }$

t = 20 seconds

Now, in horizontal direction:

Distance covered = 3 km = 3000 m

u = $\frac{Distance}{time}$

u = $\frac{3000}{20}$

u = 150 m/s

Hence, the speed of the aeroplane is 150 m/s