Question

An aeroplane touches ground at a speed of 180km/h and stops after covering a runway of 1 km calculate retardation

Answer 1

here, v=0 km/h
u = 180 km/h = 50 m/s
s = 1 km = 1000 m
applying the equation, v² - u² = 2as
⇒ 0 -(50)² = 2a×1000
⇒a = - (2500)/2000 = - 1.25 m/s²
∴retardation = 1.25 m/s²

Answer 2

Given :- v = 0km/h , u = 180km/h = 50m/s , s = 1km = 1000m

Calculate :- Retardation

Solution :- From 3rd eqn of motion...

${v}^{2} - {u}^{2} = 2as$

${0}^{2} - {50}^{2} = 2a \times 1000$

$0 - 2500 = 2a \times 1000$

$- 2500 = 2000a$

$a = \frac{ - 2500}{2000}$

$a = - 1.25 \: m {s}^{2}$

Hence ,

$retardation = 1.25m {s}^{2}$