Answer
$110\frac{km}{h}>90\frac{km}{h}$
See solution below for complete answer
Work Step by Step
$W_A=(18m)(1500kg)(9.8\frac{m}{s^2})(0.60)=158,760J$
$W_B=(30m)(1100kg)(9.8\frac{m}{s^2})(0.60)=194,040J$
$v'_A=\sqrt{\frac{2\times158,760J}{1500kg}}=14.5\frac{m}{s}$
$v'_B=\sqrt{\frac{2\times194,040J}{1100kg}}=18.8\frac{m}{s}$
$m_Av_A+m_Bv_B=m_Av{'}_A+m_Bv{'}_B$
$(1500kg)v_A=(1500kg)(14.5\frac{m}{s})+(1100kg)(18.8\frac{m}{s})$
$v_A=\frac{42,430kg \frac{m}{s}}{1500kg}=28.3\frac{m}{s}$
$E_{KA}=\frac{(1500kg)(28.3\frac{m}{s})^2}{2}=600667J$
The amount of work done by the first 15m of skidding can be calculated by
$W_{iA}=dF_f=(15m)(1500kg)(9.8\frac{m}{s^2})(0.60)=132300J$
$E_{iKA}=600667J+132300J=732967J$
$v_{iA}=\sqrt{\frac{2\times732967J}{1500kg}}=31.3\frac{m}{s}\times\frac{1km}{1000m}\times\frac{3600s}{1h}=110\frac{km}{h}>90\frac{km}{h}$