Optimizing Rally Race Time with Maximum Acceleration and Deceleration

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AI Thread Summary
In a rally race scenario, the objective is to minimize the time taken to travel 1 km while starting and ending at rest, with specified maximum acceleration and deceleration values. The initial attempt involved using equations of motion to relate distance, acceleration, and time, but the poster struggled to reach a conclusion. They also explored the AM-GM inequality but found it unhelpful. Ultimately, the poster resolved the problem independently and expressed gratitude for the assistance. The discussion highlights the complexities of optimizing race time under specific physical constraints.
Bestfrog

Homework Statement


In a rally race a pilot must travel in a minimum time ##t## a road long ##d=1 km## (the road is straight). Before he starts he is still and he must end still (so the speed at start and end is zero). The maximum acceleration is ##a_1=2,5 ms^{-2}## and the maximum deceleration is ##a_2=-3,8 ms^{-2}##. Find the minimum time t.

The Attempt at a Solution


I tried to solve it by constructing a system of the equations of motion $$d_1=\frac{1}{2} a_1 t_1^2$$
$$d_2= v_1 t_2 -\frac{1}{2}a_2 t_2^2= a_1t_1t_2 -\frac{1}{2}a_2 t_2^2$$
And I used the fact that ##d_1+d_2=d## but I can't conclude. I tried to solve it with AM-GM inequality but it doesn't work, so I think that these are the wrong paths to solve this simple problem. Any hint?
 
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No matter, I solved it :D sorry for posting
 
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