Question

An aeroplane lands and touches down the runway at a speed of 180km/h and stops after covering a distance of 1km. Calculate the retardation and the time taken by the plane to come to rest.

Answer 1

Explanation:

Initial velocity (u) = 180 km/h

Since the aeroplane comes to a stop therefore final velocity (v) = 0km/h

Distance (s) = 1

Using 3rd eq. of motion

v^2 = u^2 + 2as

0 = (180)^2 + 2a(1)

-(180)^2 = 2a

-32400/2 = a

a = -16,200 km/h^2

Since acceleration is negative therefore it is retardation.

Therefore there is a retardation of 16,200 km/h^2

Now,

Using 2nd eq. of motion

v= u+at

0 = 180 +(-16200)(t)

t = 180/16200 h

= 180/16200 * 60 min. [1 hr. = 60 min]

= 0.67 min. (approximately)

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Answer 2

Answer:

and we have to do with aeroplane