Perfect! In Case 2, the cars are moving towards each other, so, the accident will have a greater impact. The important quantity involved here is relative velocity between two objects.
Let \(v_{\text{AB}}\) represent the velocity of A wrt B. For example, if a car is travelling at \(40 \, \mathrm{km/h}\) towards the East, we can say that \(v_{\text{CE}} = 40 \, \mathrm{km/h}\). Here, C is the Car and E is the Earth.

An important equation is \(v_{\text{AB}} = -v_{\text{BA}}\). So, if A is moving at \(10 \, \mathrm{km/h}\) towards B, B is moving at \(- 10 \, \mathrm{km/h}\) towards A.
We said that the velocity of the Car wrt Earth, \(v_{\text{CE}}\) is \(30 \, \mathrm{km/h}\). What is \(v_{\text{EC}}\)?
  • \(30 \, \mathrm{km/h}\)
  • \(-30 \, \mathrm{km/h}\)
  • \(0 \, \mathrm{km/h}\)
  • \(60 \, \mathrm{km/h}\)