Question

An aeroplane flying horizontally with a speed of $360\,km\,h^{-1}$ releases a bomb at a height of $490\,m$ from the ground. If $g = 9.8\,m \,s^{-2}$, it will strike the ground at

• A. $10 \,km$
• B. $100 \,km$
• C. $1 \,km$
• D. $16 \,km$

Answer 1

Answer: (C)

$1 \,km$

Answer 2

Time taken by the bomb to fall through a height of $490\,m$ $t=\sqrt{\frac{2h}{g}}$ $=\sqrt{\frac{2\times490}{9.8}}=10\,s$ Distance at which the bomb strikes the ground = horizontal velocity $\times$ time $=360\,km\,h^{-1}\times10\,s$ $=360\,km\,h^{-1}\times \frac{10}{3600}h$ $=1\,km$