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3 years ago

If you are sitting 8.20 m from a

Physics

1 answer:

Elanso [62]3 years ago

8 0

Answer:

Explanation:

There are a lot of assumptions needed for the calculation:

first is the speaker is a point source

second the speaker is 100% efficient in its output

third the sound output propagates as a sphere

Intensity = Power / Surface Area

= 70 / (4*pi*8.20^2)

= 0.082W/m^2

Converting into dB:

= 10*log ( Intensity / (1*10^-12))

= 10*log(0.0828/ (1*10^-12))

= 109 dB

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a baby carriage is sitting at the top of a hill that is 21 m high. the carriage with the baby has a mass of 1.5 kg. the carriage

Serga [27]

Height of baby carriage from ground = 21m

Mass of carriage with baby = 1.5 kg

The carriage has potential energy by virtue of its height.

Potential energy = mgh = 1.5×10×21 = 315 J

Hence, potential energy of the carriage is 315 Joule.

7 0

4 years ago

If you traveled one mile at a speed of 100 miles per hour and another mile at a speed if 1 mile per hour, your average speed wou

Semenov [28]

Answer:

v = 1.98 mph

Explanation:

Given that,

Speed to travel one mile is 100 mph

Speed to travel another mile is 1 mph

The formula used to find your average speed is given by :

$v=\dfrac{2v_1v_2}{v_1+v_2}$

Putting the values, we get :

$v=\dfrac{2\times 100\times 1}{100+1}$

v = 1.98 mph

So, yours average speed is 1.98 mph.

7 0

3 years ago

Consider a 20 cm thick granite wall with a thermal conductivity of 2.79 W/m·K. The temperature of the left surface is held const

kozerog [31]

Answer:

The right wall surface temperature and heat flux through the wall is 35.5°C and 202.3W/m²

Explanation:

Thickness of the wall is L= 20cm = 0.2m

Thermal conductivity of the wall is K = 2.79 W/m·K

Temperature at the left side surface is T₁ = 50°C

Temperature of the air is T = 22°C

Convection heat transfer coefficient is h = 15 W/m2·K

Heat conduction process through wall is equal to the heat convection process so

$Q_{conduction} = Q_{convection}$

Expression for the heat conduction process is

$Q_{conduction} = \frac{K(T_1 - T)}{L}$

Expression for the heat convection process is

$Q_{convection} = h(T_2 - T)$

Substitute the expressions of conduction and convection in equation above

$Q_{conduction} = Q_{convection}$

$\frac{K(T_1 - T_2)}{L} = h(T_2 - T)$

Substitute the values in above equation

$\frac{2.79(50- T_2)}{0.2} = 15(T_2 - 22)\\\\T_2 = 35.5^\circC$

Now heat flux through the wall can be calculated as

$q_{flux} = Q_{conduction} \\\\q_{flux} = \frac{K(T_1 - T_2)}{L}\\\\q_{flux} = \frac{2.79(50 - 35.5)}{0.2}\\\\q_{flux} = 202.3W/m^2$

Thus, the right wall surface temperature and heat flux through the wall is 35.5°C and 202.3W/m²

6 0

3 years ago

A string vibrates at a frequency of 20Hz. what is its period?

Andreas93 [3]

We know, Period = 1/frequency = 1/20 sec.

So, your final answer is 0.05 sec

Hope this helps!

7 0

3 years ago

While i was jogging, i wad able to run 5 miles in thirty minutes. from this information, we can determine my?

Llana [10]

You can only determine the speed since the only info we know is how much you ran in how long of a time.

7 0

3 years ago

Read 2 more answers