Answer:
[tex]6.5\%\ of\ u_1[/tex]
Explanation:
[tex]m_{1}[/tex] = Mass of ball = 0.12 kg
tex]m_{2}[/tex] = Mass of bottle = 2.4 kg
[tex]u_{1}[/tex] = Initial velocity of ball
[tex]u_{2}[/tex] = Initial velocity of bottle
[tex]v_{1}[/tex] = Final velocity of ball = [tex]-0.3u_{1}[/tex]
[tex]v_{2}[/tex] = Final velocity of bottle
As linear momentum is conserved
[tex]m_{1}u_{1}+m_{2}u_{2}=m_{1}v_{1}+m_{2}v_{2}\\\Rightarrow 0.12u_{1}+2.4\times 0=-0.12(0.3u_{1})+2.4v_{2}\\\Rightarrow 0.156u_1=2.4v_2\\\Rightarrow \frac{v_2}{u_1}=0.065\\\Rightarrow v_2=0.065\times 100\times u_1\\\Rightarrow v_2=6.5\%\ of\ u_1[/tex]
The bottle's speed is [tex]6.5\%\ of\ u_1[/tex]