Answer:
115 km/h
Explanation:
[tex]m_1[/tex] = Mass of car A = 690 kg
[tex]m_2[/tex] = Mass of car B = 520 kg
g = Acceleration due to gravity = 9.81 m/s²
a = Acceleration
u = Initial velocity
v = Final velocity
[tex]a=\mu g\\\Rightarrow a=0.75\times 9.81\\\Rightarrow a=7.3575\ m/s^2[/tex]
[tex]v^2-u^2=2as\\\Rightarrow v=\sqrt{2as+u^2}\\\Rightarrow v=\sqrt{2\times 7.3575\times 6+0^2}\\\Rightarrow v=9.396\ m/s[/tex]
[tex]m_1u_1 + m_2u_2 =(m_1 + m_2)v\\\Rightarrow u_1=\frac{(m_1 + m_2)v-m_2u_2}{m_1}\\\Rightarrow u_1=\frac{(690+520)9.396-520\times -\frac{74}{3.6}}{690}\\\Rightarrow u_1=31.96\ m/s[/tex]
Converting to km/h
[tex]31.96\times 3.6=115.056\ km/h[/tex]
Initial velocity of car A = 115 km/h
