Answer:
73 db
Explanation:
A single air conditioner is equivalent to 70 dB frequency. An extra air conditioning unit would therefore double the sound frequency. It does not, however, double the decibels to 140 dB. Instead, it adds only 3 dB to the 70 dB, making the total decibels of two air conditioning units equal to 73 db
Hence the correct option is b that is 73 db
Answer:

Explanation:
we know that



as we see that 
relative error
Where X_1 IS HEIGHT OF ROCK
IS THE HEIGHT OF ROAD
= uncertainity in measuring distance

Putting all value to get uncertainity in angle

solving for
we get

Steel paper clip because it can be moved by the magnet and it is lighter than the iron nail
Answer:
As 28m/s = 28m/s
Explanation:
r = the radius of the curve
m = the mass of the car
μ = the coefficient of kinetic friction
N = normal reaction
When rounding the curve, the centripetal acceleration is

therefore



As 28m/s = 28m/s
Understanding Newtons second law that everything has an equal and opposite reaction. The reaction force from a balloons air being pushed out is the preasurized air it had to push out into the open air.