Question

A bullet moving with velocity 200 cm/s penetrates a wooden block and comes to rest after traversing 4cm inside it. What velocity is needed for travelling a distance at 9cm in same block (Ans. in cm/s)

Answer 1

Use the third equation of motion, i.e,

v2=u2+2×a×s,v2=u2+2×a×s,

First let's find the retardation of bullet as it penetrates the wooden block.

Final velocity, v=0v=0

Initial velocity, u=200cmsecu=200cmsec

Distance travelled, s=4cms=4cm

⟹02=2002+2×a×4⟹02=2002+2×a×4

⟹a=−5000cmsec2⟹a=−5000cmsec2

Now, for the bullet to travel a distance, s=9cms=9cm it has to have a velocity uu given by,

02=u2+2×(−5000)×902=u2+2×(−5000)×9

⟹u=300cm/sec

Answer 2

Explanation:

here is the answer

hope it helps you