Question

A bullet when first into a target loses half
of its velocity after penetrating 20cm.
Further distance of penetration before it
comes to rest is
6.66 cm
3.33 cm
12.5 cm
10 cm​

Answer 1

Answer:

6. 66 cm

Explanation:

Given :

Initial velocity ( u ) = v

Final velocity ( v ) = v / 2

Distance ( s ) = 20 cm

Let, the further distance of penetration before it comes to rest be x.

V² = U² - 2as

( v/2 ) ² = V² - 2a * 20

40a = V² - v² / 4

40a = 3v²/ 4 ----- ( 1.)

and,

V² = U² +2as

v² = 0 +2a * ( 20 +x)

v² = 2* 3/ 160 v² (20 + x) [ from 1. ]

1 = 3 /80( 20 +x)

x = 80 / 3 - 20

x = 80-60/3

x = 20/3

x = 6.66 cm

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