Let's meet together #4 - a Physics problem

Since the motorbike starts moving at 6 am, I referred to 6 am as hour zero. So my calculations were done in terms of the hours past hour zero (so 7 am is referred to as hour 1, 8 am as hour 2, and so on). So, at $t = 0$ , the position $x_{m_0}$ of the motorbike is 0 km, at point $A$ . Since the car starts moving at 7 am, which is one hour after the motorbike started moving, its position is still at point B, 300 km, after the motorbike has already traveled 50 km.

From the table above, knowing that the bike starts at hour 1 and that it must always be at the midpoint between the motorbike and the car, we must simply find the midpoint between the motorbike's position at hour 1 and the car's position at hour 1. From the table, we can see that at 7 am (hour 1), the motorbike is at $x=50 km$ , and the car is at $x=300 km$ . So, the midpoint between those two positions is simply the average of 50 and 300: 175. Therefore, the bike starts moving when 175 km from both the motorbike and the car.