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storchak [24]
3 years ago
12

At the race track, one race car starts its engine with a resulting intensity level of 104.0 dB at point P. Then 6 more cars star

t their engines. If the other 6 cars each produce the same intensity level at point P as the first car, what is the new intensity level with all 7 cars running?
Physics
1 answer:
dem82 [27]3 years ago
8 0

To solve the problem it is necessary to apply the concepts related to sound intensity. The most common approach to sound intensity measurement is to use the decibel scale:

\beta (dB) = 10log_{10}(\frac{I}{I_0})

Where,

I_0 = 1*10^{-12} is a reference intensity. It is the lowest or threshold intensity of sound a person with normal hearing can perceive at a frequency of 1000 Hz.

I = Sound intensity

Our values are given by,

\beta = 104dB

\#Autos = 7

For each auto the intensity would be,

104 = 10log\frac{I}{1*10^{-12}}

10.4= log_{10} (\frac{I}{10^{-12}})

10^{10.4}*10^{-12}=I

I = 0.02511W/m^2

Therefore the sound intesity for the 7 autos is

I= 7* 0.02511

I = 0.1748W/m^2

The sound level for the 7 cars in dB is

\beta (dB) = 10log_{10}(\frac{0.1748}{1*10^{-12}})

\beta (dB) = 112.42dB

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vichka [17]

To solve this problem we will apply the expression of charge per unit of time in a capacitor with a given resistance. Mathematically said expression is given as

q(t) = e^{-\frac{t}{(R*C)}}

Here,

q = Charge

t = Time

R = Resistance

C = Capacitance

When the charge reach its half value it has passed 10ms, then the equation is,

\frac{1}{2}*q_{final} = e^{-\frac{0.01}{(R*C)}}

Ln(\frac{1}{2}) = -\frac{0.01}{RC}

- RC = \frac{0.01}{Ln(1/2)}

RC = 0.014s

We know that RC is equal to the time constant, then

T = RC  = 0.014s = 14ms

Therefore the time constant for the process is about 14ms

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3 years ago
What is the cooling power P? Recall that the rate at which energy is removed, also called the cooling power, was described earli
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36.667

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3 years ago
A block slides down a slope inclined at 37 degrees. If the slope is frictionless and the block starts off at rest, how fast is i
lianna [129]

Answer:

Vf= 3.435 m/s

Explanation:

Given:

Initial velocity Vi =0 m/s (starting from Rest position)

θ = 37⁰

Distance S = 1 m

To find: Final Velocity Vf=?

fist we have to find the down slope net acceleration a = g sin θ

a= 9.81 sin  37⁰ = 5.9 m/s²

By 3rd equation of motion

2 a S= Vf² - Vi²

Vf = Square root ( 2 × 5.9 m/s²  × 1  + 0 m/s)

Vf = Square root (11.8)

Vf= 3.435 m/s

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3 years ago
What is energy? Where does it come from? What does it do? Explain in 5 or more sentences please! :)
Vlada [557]

Answer:

Energy is defined as the ability to do work. Forms of energy could be kinetic energy or potential energy. Thermal or heat energy can originate from a hot object such as the sun. Energy is used to produce work. Electrical energy for lighting purposes and heating in homes and factories.

Explanation:

Energy is defined as the ability to do work and can be in various forms such as kinetic energy, potential energy, thermal, chemical, electrical energy etc.

Energy origination depends on the type of energy form in discussion. Thermal or heat energy can originate from a hot object such as the sun or an iron box, chemical energy originates from the interaction of atoms and molecules and electrical energy can be initiated by movements of electrons.

Energy is used to produce work. Different forms of energy can do different tasks such as;

Heat energy for heating water

Electrical energy for lighting purposes

Geothermal energy for producing heat and electricity

Nuclear energy for production of nuclear power

Chemical energy for facilitating chemical reactions

4 0
3 years ago
A girl on a bike is moving at a speed of 1.40 m/s at the start of a 2.45 m high and 12.4 m long incline. The total mass is 60.0
Scrat [10]

Answer:

Explanation:

Given that,

Initial speed of the girl is

u = 1.4m/s

Height she is going is

H = 2.45m

Incline plane she will pass to that height

L = 12.4m

Mass of girl and bicycle is

M=60kg

Frictional force that oppose motion is

Fr = 41N

Speed at lower end of inclined plane

V2 = 6.7m/s

Work done by the girl when the car travel downward

Using conservation of energy

K.E(top) + P.E(top) + work = K.E(bottom) + P.E(bottom) + Wfr

Where Wfr is work done by friction

Wfr = Fr × d

P.E(bottom) is zero, sicne the height is zero at the ground

K.E is given as ½mv²

Then,

½M•u² + MgH + W = ½M•V2² + 0 + Fr×d

½ × 60 × 1.4² + 60×9.8 × 2.45 + W = ½ × 60 × 6.7² + 41 × 12.4

58.8 + 1440.5 + W = 1855.1

W = 1885.1 —58.8 —1440.5

W = 355.8 J

8 0
3 years ago
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