Can someone please answer 5-7

How does the intensity of a sound wave change if the distance from the

Alex17521 [72]

Answer:

The new intensity decreases by a factor of 16.

Explanation:

The intensity of sound wave is given by :

$I=\dfrac{P}{A}$

P is power

A is area

$I=\dfrac{P}{4\pi r^2}$

or

$I\propto \dfrac{1}{r^2}$ , r is distance from the source

If the distance from the source is increased by a factor of 4, r' = 4r

So,

$I'=\dfrac{1}{r'^2}\\\\I'=\dfrac{1}{(4r)^2}\\\\I'=\dfrac{1}{16}\times \dfrac{1}{r^2}\\\\I'=\dfrac{I}{16}$

So, the new intensity decreases by a factor of 16.

8 0

3 years ago

Q3. At an altitude of 6679 km above the center of the Earth, the

EastWind [94]

Answer:

5524.8 m/s

Explanation:

Given that,

Altitude above the surface of earth is 6679 km, the Space Station can complete one orbit in 1.5 hours. We need to find the average speed of the ISS. The average speed of its orbit is given by :

$v=\sqrt{\dfrac{GM}{R}}$

R is distance from Earth

R = r + d, r is the radius of Earth

R = 6371 + 6679

R = 13050 km

So,

$v=\sqrt{\dfrac{6.67\times 10^{-11}\times 5.972 \times 10^{24}}{13050\times 10^3}}\\\\v=5524.8\ m/s$

or

Hence, the average speed of ISS is 5524.8 m/s.

4 0

3 years ago

60. The label on a box of cereal gives the mass of cereal in two units: 978 grams and 34.5 oz. Use this information to find a co

Anastaziya [24]

Answer : The mass of cereal in two units are, 34.815 oz and 978.075 grams respectively.

Explanation :

As there are two systems for measuring the units which are English and Metric system.

The Metric System measured the things in meters, grams, liters, etc and adds prefixes like kilo, milli and centi to the count orders of the magnitude.

The English system measured the things in feet, inches, pounds, mile, etc.

As we are given the mass of cereal in 978 grams that means 987 grams is in metric unit. Now we have to convert metric unit into English unit.

Conversion factor used : (1 oz = 28.350 g)

As, 28.350 grams = 1 oz

So, 987 grams = $\frac{987\text{ grams}}{28.350\text{ grams}}\times 1oz$

= 34.815 oz

As we are given the mass of cereal in 34.5 oz that means 34.5 oz is in metric unit. Now we have to convert metric unit into English unit.

Conversion factor used : (1 oz = 28.350 g)

As, 1 oz = 28.350 grams

So, 34.5 oz = $\frac{34.5\text{ oz}}{1\text{ oz}}\times 28.350\text{ grams}$

= 978.075 grams

Therefore, the mass of cereal in two units are, 34.815 oz and 978.075 grams respectively.

7 0

3 years ago

Monochromatic electromagnetic radiation illuminates an area of a surface. The electric and magnetic fields of the waves are then

emmasim [6.3K]

Answer:

c) True. factor four

Explanation:

The energy density of an electromagnetic wave is given by

u = ½ ε₀ E² = B² / 2μ₀

Where ε₀ is the dielectric constant and μ₀ the magnetic permittivity.

Let's apply this equation to the present case

If we double the electro field

E ’= 2 E₀

u’= ½ ε₀ (2E₀)²

u’= ½ ε₀ Eo² 4

u’= 4 u₀

Therefore the energy is multiplied by four

Let's check the answers

a) False

b) False

c) True

d) False

e) False

6 0

3 years ago

Bowl of water A bowl full of water is sitting out in a pouring rainstorm. Its surface area is 500 cm2. The rain is coming straig

vova2212 [387]

Answer: 4.9 x 10-3 N

Explanation:

A = 500cm^2 = 5 x 10^-2 m^2

V = 5 m/s

R = 10^-3 g/cm^2.sec = 10^-2kg/m^2 . sec

Prain water = R / V = 10^-2 / 5 = 2 x 10-3 kg/m^3

For the stationary bowl,

dm/dt =pAv= RA

F= dp/dt = (dm/dt) v = RAv = 2.5 x 10^-3 N

Bowl moving upwards to speed u = 2 m/s

dm/dt = pA ( v + u) / v

F = dp/dt = (dm/dt)(v+u) = RA (v+u)^2 / v = 4.9 x 10^-3 N

5 0

3 years ago