Answer:
100000 m/s in the opposite direction
22369.4185194 mph
Explanation:
[tex]m_1[/tex] = Mass of superhero
[tex]m_2[/tex] = Mass of asteroid = [tex]1000m_1[/tex]
[tex]v_2[/tex] = Speed at which the asteroid is thrown = 100 m/s
[tex]v_1[/tex] = Recoil velocity
Here the linear momentum of the system is conserved
[tex]m_1v_1+m_2v_2=0\\\Rightarrow v_1=-\dfrac{m_2v_2}{m_1}\\\Rightarrow v_1=-\dfrac{1000m_1\times 100}{m_1}\\\Rightarrow v_1=-100000\ m/s[/tex]
The recoil speed is 100000 m/s in the opposite direction
Converting to miles per hour
[tex]\dfrac{10000}{1609.34}\times 3600=22369.4185194\ mph[/tex]
The speed is 22369.4185194 mph