A car A travelling at 161 km/hr is 676 m directly behind another car B travelling at 29.0 km/hr.
What must the deceleration be in order for car A to avoid collision with car B?
The Attempt at a Solution
So the initial velocity of car A is 161 km/hr and we're trying to find the deceleration (or negative acceleration as I'll make it here) of it. Assuming car B has no acceleration, the distance gap between them will be: 676 m + 29.0 km/hr - (161 km/hr + negative acceleration).
I tried to calculate it manually by finding the distance every second, but it takes too long on an exam and I can't find any formula that fits this criteria of information. How do I find the formula for the exact distance at a given point in time given this information?