Question

An aeroplane moving horizontally with a speed of 720 km/h drops a food packet, while flying at a height of 396.9 m. The time taken by a food packet to reach the ground and its horizontal range is (Take g = 9.8 m/sec²)

• A. 3 sec and 2000 m
• B. 5 sec and 500 m
• C. 8 sec and 1500 m
• D. 9 sec and 1800 m

Answer 1

Answer: (D)

9 sec and 1800 m

Answer 2

Time of descent $t = \sqrt{\frac{2h}{g}}$ $= \sqrt{\frac{2 \times 396.9}{9.8}}$

⇒ $t = 9sec$

and horizontal distance $S = u \times t$

$S = \left( \frac{720 \times 5}{18} \right) \times 9$ $= 1800m$