A sound wave passes through an area of 5.5 m Square with an intensity of 7.2 x 10 exp-5 W/m square. What is the power of this sound ? 1- P = 396 x 10 exp -8 W
2- P = 3.96 x 10 exp -4 W
3- P = 39.6 x 10 exp -9 W
4- P = 0.38 x 10 exp -3 W

i think the answer would be reserve.

the minimum constant speed at which she can catch the train is 2.7 m/s

given:

acceleration = 0.6

time = 4.5 s

to find:

velocity = ?

formula used:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

solution:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

v = 0 + (0.6 × 4.5)

v = 2.7 m/s

the minimum constant speed at which she can catch the train is 2.7 m/s