What is the weight of a 42 kg object if the object was on the moon?

A concert loudspeaker suspended high off the ground emits 39 w of sound power. a small microphone with a 1.0 cm2 area is 60 m fr

Gelneren [198K]

As we know that intensity of sound is defined as power received per unit area

so here the power of source is given as

$P = 39 W$

distance of microphone is given as

$d = 60 m$

now if loudspeaker is considered as spherical source then we will have

$Intensity = \frac{power}{area}$

$Intensity = \frac{39}{4\pi r^2$

here

r = d = 60 m

$Intensity = \frac{39}{4\pi (60^2)}$

$Intensity = 0.86 \times 10^{-3} W/m^2$

7 0

3 years ago

What might Earth be like if it had never been hit by the theoretical protoplanet Orpheus?

Dafna1 [17]

Answer:

If Earth hadn't been hit by Orpheus, it would be covered by ocean, with perhaps a few mountaintops emerging through the water. There would be no humans, but there could be other forms of life. Earth would rotate rapidly, as the moon would not be present to produce the tidal friction that slows Earth's rotation today

7 0

2 years ago

1. in which lover of Earth are temperature and pressure greatest? 1-A B C D

alukav5142 [94]

Answer:

D

Explanation:

because it's the deepest

7 0

3 years ago

If the current density in a wire or radius R is given by J-k+5,0F wire? R, what is the current in the wire?

Deffense [45]

Answer:

I = $R^{2}$ (K+5)

Explanation:

Given :

J = k+5

Now selecting a thin ring in the wire of radius "r" and thickness dr.

Current through the thin ring is

dI = J X 2πrdr

dI = (K+5) x 2πrdr

Now integrating we get

I = $\int_{0}^{R} = (K+5).2\pi rdr$

I = (K+5) 2π $\int_{0}^{R} rdr$

I = (K+5) 2π $\frac{R^{2}}{2}$

I = $R^{2}$ (K+5)

8 0

3 years ago

Why has the atomic model changed over time

inysia [295]

The first model of the atom was developed by JJ Thomson in 1904, who thought that atoms were composed purely of negatively charged electrons. This model was known as the 'plum pudding' model.

This theory was then disproved by Ernest Rutherford and the gold foil experiment in 1911, where Rutherford shot alpha particles at gold foil, and noticed that some went through and some bounced back, implying the existence of a positive nucleus.

In 1913, Niels Bohr proposed a model of the atom where the electrons were contained within quantized shells that orbited the nucleus. This was because it was impossible for the cloud of negative electrons proposed by Rutherford to exist, as the negative electrons would be drawn to the positive nucleus, and the atom would collapse in on itself.

In 1926, the Austrian physicist Erwin Schrödinger created a quantum mechanical model of the atom by combining the equations for the behavior of waves with the de Broglie equation to generate a mathematical model for the distribution of electrons in an atom.

However the model used today is closest to the Bohr model of the atom, using the quantized shells to contain the electrons.

For more info:

http://chemistry.about.com/od/chemistryglossary/a/debroglieeqdef.htm

7 0

2 years ago