The plane touches the landing strip at a speed of V0 = 60 m / s and stops after running the path

The plane touches the landing strip at a speed of V0 = 60 m / s and stops after running the path L = 1800 m. What is the speed V of the plane when it ran the distance S = 450 m along the strip?

Data: V0 (speed at the moment of touching the landing strip) = 60 m / s; L (full braking distance) = 1800 m; S (considered distance) = 450 m.

1) Constant aircraft acceleration on the landing strip: L = V0 ^ 2 / 2a and a = V0 ^ 2 / 2L = 60 ^ 2 / (2 * 1800) = 1 m / s2.

2) Speed at 450 m: S = (V0 ^ 2 – V2) / 2a and V = √ (V0 ^ 2 – 2a * S) = √ (60 ^ 2 – 2 * 1 * 450) = √2700 = 51.96 m / s.

Answer: At the 450 m mark, the plane had a speed of 51.96 m / s.