Motion in a Plane - Result Question 28
31. A bullet is fired from a gun with a speed of 1000 $m / s$ in order to hit a target $100 m$ away. At what height above the target should the gun be aimed? (The resistance of air is negligible and $.g=10 m / s^{2})$
[1995]
(a) $5 cm$
(b) $10 cm$
(c) $15 cm$
(d) $20 cm$
Topic 3: Projectile Motion
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Answer:
Correct Answer: 31. (a)
Solution:
- (a) Speed of the bullet (v) $=1000 m / s$ and horizontal distance of the target $(s)=100 m$. Time taken to cover the horizontal distance $(t)$ $=\frac{100}{1000}=0.1 sec$.
During this time, the bullet will fall down vertically due to gravitational acceleration.
$\therefore$ height $(h)=u t+\frac{1}{2} g t^{2}$
$ \begin{aligned} & =(0 \times 0.1)+\frac{1}{2} \times 10(0.1)^{2} \\ & =0.05 m=5 cm \end{aligned} $
