Rotational Motion Question 213
Question: A bullet of mass 10 g and speed 500 m/s is fired into a door and gets embedded exactly at the centre of the door. The door is 1.0 m wide and weighs 12 kg. It is hinged at one end and rotates about a vertical axis practically without friction. The angular speed of the door just after the bullet embeds into it will be:
Options:
A) 6.25rad/sec
B)0.625 rad/sec
C) 3.35 rad/sec
D)0.335 rad/sec
Show Answer
Answer:
Correct Answer: B
Solution:
[b]
Letx= distance between hinge and centre of the door $=L/2=\frac{1}{2}=0.5m$
As per conservation of angular momentum $mvx=I\omega $
$\Rightarrow w=\frac{mvx}{I}=\frac{0.01\times 500\times 0.5}{\frac{1}{3}\times 12\times {{(1)}^{2}}}=0.625rad/s$
