Question

An aeroplane lands with a velocity of 270 km h$^{-1}$ and comes to rest, after covering a runaway of 1000 m. Calculate (i) retardation (ii) time in which aeroplane vomes to rest.​

Answer 1

Correct Question:-

An aeroplane lands with a velocity of 270 km h$^{-1}$ and comes to rest, after covering a runaway of 1000 m. Calculate (i) retardation (ii) time in which aeroplane comes to rest.

Given:-

u = 270 km h$^{-1}$

v = 0

S = 1000 m

where u means initial velocity;

v means final velocity and

S means distance

To find:-

• Retardation
• Time in which aeroplane comes to rest.

Solution:-

Using third equation of motion

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

$\Longrightarrow (0) {}^{2} - (75) {}^{2} = 2 \times a \times 1000.$

$\Longrightarrow0 - 5625 = 2000a \\ \\ </h3><p></p><h3>\Longrightarrow \: a = \frac{ - 5625}{2000} ms {}^{ - 2} \\ \\ = - 2.8125 \: ms {}^{ - 2}$

Therefore retardation = (–a)

$= - ( - 2.8125 \: ms {}^{ - 2} ) \\ \\ = 2.8125 \: ms {}^{ - 2} .$

Now, using first equation of motion

v = u + at

$\Longrightarrow0 = 75 - 2.8125 \times t \\ \\ </h3><p></p><h3>\Longrightarrow \: t = \frac{75}{2.8125} \\ \\ = 26.67s.$

Time in which aeroplane comes to rest = 26.67s.

Answer 2

Answer:

26.67s will be the correct answer hope it helps you