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A bullet of mass 20 g has an initial spe...

A bullet of mass 20 g has an initial speed of `1 ms^(-1)` just before it starts penetrating a mud wall of thickness 20 cm. If the wall offers a mean resistance of `2.5 xx 10^(-2)N` the speed of the bullet after emerging from the other side of the wall is close to:

A

`0.3 ms^(-1)`

B

`0.1 ms^(-1)`

C

`0.7 ms^(-1)`

D

`0.4 ms^(-1)`

Text Solution

Verified by Experts

The correct Answer is:
C
`F.x = (1)/(2) mv_(f)^(2)- (1)/(2) mv_(i)^(2)`
`rArr-2 xx 10^(-2) xx 0.2 = (1)/(2) xx 20 xx 10^(-3) (v_(f)^(2)- 1^(2))`
`rArr - 0.5= v_(f)^(2)-1^(2)`
`rArr v_(f)^(2)= 0.5`
`rArr v_(f)= (1)/(sqrt2) m//s= 0.7 m//s`
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