Answer:168 W
Explanation:
Given
Power needed [tex]P=42 W[/tex]
initial Launch velocity is v
Energy of projectile when it is launched [tex]E=\frac{1}{2}mv^2[/tex]
[tex]Power=\frac{Energy}{time}[/tex]
[tex]Power=\frac{E}{t}[/tex]
[tex]42=\frac{\frac{1}{2}mv^2}{t}--------1[/tex]
Power when it is launched with 2 v
[tex]E_2=\frac{1}{2}m(2v)^2=\frac{4}{2}mv^2[/tex]
[tex]P=\frac{2mv^2}{t}---------2[/tex]
Divide 1 & 2 we get
[tex]\frac{42}{P}=\frac{1}{2\times 2}[/tex]
[tex]P=42\times 4=168 W[/tex]
