Kinematics -- How do I apply them to different problems? 1. The problem statement, all variables and given/known data A Jet plane lands with a speed of 100 m/s and can accelerate at a maximum rate of -5.00 m/s^2 as it comes to a rest. A) From the instant the plane touches the runway, what is the min. time needed before it can come to a rest? B) Can this plane land on a small tropical island airport where the runway is 0.800 km long? 2. Relevant equations Constant acceleration (Velocity as a function of time): Vf=Vo + at Displacement as a function of time: X = Vo + t(1/2)(a)(t^2) Velocity as a function of displacement: V^2 = Vo^2 + 2ax 3. The attempt at a solution So I'm having a really tough time figuring out which equation to use where. I've deciphered what we're given. Vf: 100 m/s a = -5.00 m/s^2 The problem is asking in A) to find the time B) once we've found the time, we plug it back into one of the original equations (I would say the second one) to find the distance required for the plane to stop. So, I take a stab at the first equation: Vf = Vo + at Vf = 100 m/s = Vo (I don't know the initial velocity) + (-5.00 m/s^2)(t) So trying to solve for t: t= 105 m/s^3 - Vo That doesn't make sense really. I keep getting hung up on these kinematic equations -- they keep coming back to haunt me in the next chapter when working on not only the x-axis but now the y-axis as well.