Question

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

Answer 1

to penetrate upto 9cm,the velocity required is 450m/s

Answer 2

Given : For initial case- >

u = 200 m/s

s = 4 cm = 0.04 m

As the bullet stops in the wood after penetration

so, v = 0 m/s


We know that

${v}^{2} - {u}^{2} = 2as$


so, 0 - 200^2 = 2(a)(0.04)


so, -40000 = 0.08a


so, a = -40000/0.08 = -500000 m/s^2


For Second case ->

v = 0 m/s

s = 9 cm = 0.09 m

a = -500000 m/s^2

so, putting the values in formula

0^2 - v^2 = 2(-500000)(0.09)

so, v^2 = 90000

so, v = √90000

so v = 300 m/s

So the velocity required to travel 9cm in the same block will be 300 m/s.