Answer:
atm
Explanation:
The pressure at the bottom of any liquid column is equal to product of density of the liquid , gravitational acceleration constant (g) and height of the water column
Thus, 
Substituting the given values, we get -
kg/m3
m/s^2
meters
atm
Answer
given,
distance between A and B is equal to 5 m
let x be the distance of loud speaker from the source A
For constructive interference, path difference = mλ
x - (5 - x ) = 0 , for m = 0
2 x - 5 = 0
2 x = 5
x = 2.5 cm
For destructive interference

m = 0



x = 4 , 1 cm
Speedometer of car read instantaneous speed of course. Its because when you stop it instantaneous show 0. If speedometer show average speed there should be different value than 0 (much greater) just when you stop.
Maybe there are car with speedometer with average speed but the time from which the average is taken is extremely small. Its simply instantaneous speed.
The result wave Will have a greater amplitude than both waves