Question

physics class 11 science

Answer 1

HEY frnd here is ur ans.....

GIVEN:

Initial velocity (u) = 20km/h

final velocity (v) = 0

Distance (s) = 2km

speed of bird = 60 km/h

by using formula :

v^2 = u^2 +2as

by putting the values...

0 = (20)^2 + 2×a×2

0 = 400 + 4a

4a = -400

a = -400/4 = - 100km/h^2

Now,,

time taken to travel 2km to reach platform

v = u + at

by putting the value

0 = 20 - 100t

t = 1/5 hr

Now,

Distance travel in 1/5 hr.

Distance = speed × time

Distance = 60 × 1/5 =12 km .... Ans. ;)

Hope it helps you✌✌

Thankyou ☺

SWEETY ⚡⚡

Answer 2

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

Final velocity 'v' is 0 because it is assumed that the train is supposed to stop when it reaches the pole.

initial velocity = 20 km/hr ...(given)

s = 2 km, the distance of the train from the pole.

$v^2=u^2+2as\\0=20^2+2*a*2\\0=400+4a\\4a=-400\\a=-100\ km/hr^2$

Now,

$v=u+at\\0=20+(-100)*t\\-20=-100t\\\\t=\frac{-20}{-100} \\\\t=\frac{1}{5}\ hr$

Distance = speed (of bird) x time (above calculated)

$Distance=60*\frac{1}{5}\\\\\boxed{Distance=12\ km}$