Answer:
The initial speed of bullet is "164 m/s".
Explanation:
The given values are:
mass of bullet,
[tex]m'=9.00 \ g[/tex]
or,
[tex]=0.009 \ kg[/tex]
mass of wooden block,
[tex]m=1.20 \ kg[/tex]
speed,
[tex]s=0.390 \ m[/tex]
Coefficient of kinetic friction,
[tex]\mu=0.20[/tex]
As we know,
The Kinematic equation is:
⇒ [tex]v^2=u^2+2as[/tex]
then,
Initial velocity will be:
⇒ [tex]u=v^2-2as[/tex]
[tex]=v^2-2 \mu gs[/tex]
On substituting the given values, we get
⇒ [tex]u=\sqrt{0-2\times 0.20\times 9.8\times 0.390}[/tex]
[tex]=\sqrt{-1.5288}[/tex]
[tex]=1.23 \ m/s[/tex]
As we know,
The conservation of momentum is:
⇒ [tex]mu=m'u'[/tex]
or,
⇒ Initial speed, [tex]u'=\frac{mu}{m'}[/tex]
On substituting the values, we get
⇒ [tex]=\frac{1.20\times 1.23}{0.009}[/tex]
⇒ [tex]=\frac{1.476}{0.009}[/tex]
⇒ [tex]=164 \ m/s[/tex]
