Kinematics Question 612
Question: A bullet it’s fired with a speed of $ 1500m\text{/}s $ in order to hit a target 100 m away. If $ g=10m\text{/}s^{2}. $ The gun should be aimed
Options:
A) 15 cm above the target
B) 10 cm above the target
C) 2.2 cm above the target
D) directly towards the target
Show Answer
Answer:
Correct Answer: C
Solution:
[c] The bullet performs a horizontal journey of 100 cm with constant velocity of 1500 m/s. The bullet also performs a vertical journey of h with zero initial velocity and downward acceleration g.
$ \therefore $ For horizontal journey, $ \text{time }( \text{t} )=\frac{\text{distance}}{\text{Velocity}} $
$ \therefore t=\frac{100}{1500}=\frac{1}{15}\text{sec }…\text{(1)} $
The bullet performs vertical journey for this time.
For vertical journey, $ \text{h}\text{=}\text{ut+}\frac{\text{1}}{\text{2}}\text{g}{{\text{t}}^{\text{2}}} $
$ \text{h=0+}\frac{1}{2}\times 10\times {{( \frac{1}{15} )}^{2}} $
$ \text{or, h=}\frac{20}{9}\text{ cm = 2}\text{.2cm} $
