Physics - Kinematics Question with Solution | TestHub

When two objects move towards each other, their relative speed is the sum of their individual speeds. Relative speed$V_{rel}=V_A+V_B=10\text{ m/s}+15\text{ m/s}=25\text{ m/s}$. For them to completely cross each other, the total distance to be covered is the sum of their lengths:$D_{total}=L_A+L_B=100\text{ m}+150\text{ m}=250\text{ m}$. Time taken$t=\frac{D_{total}}{V_{rel}}=\frac{250\text{ m}}{25\text{ m/s}}=10\text{ s}$.