# Need help with physics airplane runway question

## Homework Statement

length of runway for airplane 1.5miles, accelerate at 3.0m/s^2 decelerate at 2.1m/s
What length of time is available from the start of the motion to decide on a course of action (take off or abort)

## Homework Equations

d=a*t 3.0m/s/-2.1m/s

## The Attempt at a Solution

so far we have 804 seconds acceleration and -1149 seconds for deceleration

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## Homework Equations

d=a*t 3.0m/s/-2.1m/s
The airplane is accelerating, or decelerating. This is the equation for constant speed.

## The Attempt at a Solution

so far we have 804 seconds acceleration and -1149 seconds for deceleration
After 804 seconds of 3 m/s^2 acceleration, the speed of the airplane will be 1206 m/s.
It will have covered 970 km

suppose the airplane is accelerating until time T. How many meters does it move?
If the airplane starts decelerating at time T, how long does it take before it stands still?
How many meters does it move in that time?
The sum of these 2 distances should be equal to the length of the runway, in the limiting case
where the airplane is just able to stop in time. This will give you an equation that you can solve
for T.