Help me please!!!!!!!!!!!!!/ Science

If a cup of coffee has temperature 95∘C95∘C in a room where the temperature is 20∘C,20∘C, then, according to Newton's Law of Coo

lina2011 [118]

Answer:

T = 76.39°C

Explanation:

given,

coffee cup temperature = 95°C

Room temperature= 20°C

expression

$T( t ) = 20 + 75 e^{\dfrac{-t}{50}}$

temperature at t = 0

$T( 0 ) = 20 + 75 e^{\dfrac{-0}{50}}$

T(0) = 95°C

temperature after half hour of cooling

$T( t ) = 20 + 75 e^{\dfrac{-t}{50}}$

t = 30 minutes

$T( 30 ) = 20 + 75 e^{\dfrac{-30}{50}}$

$T( 30 ) = 20 + 75 \times 0.5488$

T(30) = 61.16° C

average of first half hour will be equal to

$T = \dfrac{1}{30-0}\int_0^30(20 + 75 e^{\dfrac{-t}{50}})\ dt$

$T = \dfrac{1}{30}[(20t - \dfrac{75 e^{\dfrac{-t}{50}}}{\dfrac{1}{50}})]_0^30$

$T = \dfrac{1}{30}[(20t - 3750e^{\dfrac{-t}{50}}]_0^30$

$T = \dfrac{1}{30}[(20\times 30 - 3750 e^{\dfrac{-30}{50}} + 3750]$

$T = \dfrac{1}{30}[600 - 2058.04 + 3750]$

T = 76.39°C

4 0

3 years ago

What is the primary role of the respiratory system in living organisms?

Papessa [141]

I think its b but not sure

3 0

3 years ago

An object with a resistance of 28 Ω has 76 V applied to it. How much electric current is going through this object? Answer in un

12345 [234]

Answer : The electric current of a circuit is, 2.8 A.

Explanation :

Using Ohm's law :

$V=I\times R$

Or,

$I=\frac{V}{R}$

where,

R = resistance of a circuit = 28 Ω

V = voltage of circuit = 76 volts = 76 V

I = current flowing in a circuit = ?

Now put all the given values in the above formula, we get :

$I=\frac{V}{R}$

$I=\frac{76V}{28\Omega }$

$I=2.8A$

Therefore, the electric current of a circuit is, 2.8 A

5 0

3 years ago

In an inertia balance, a body supported against gravity executes simple harmonic oscillations in a horizontal plane under the ac

avanturin [10]

Answer:

2) f = 0.707 Hz

Explanation:

Given m₁ = 1.0 kg , f₁ = 1.0 Hz

So using the equation

f₁ = ( 1 / 2 π ) * √K / m₁

Solve to determine K' constant of spring

K = m * ( 4 π ² * f ² )

K = 1.0 kg * ( 4 π ² 1.0² Hz )

K = 39.4784176

So given 2.0 kg the frequency can be find using formula

f₂ = ( 1 / 2 π ) * √K / m₂

f₂ = ( 1 / 2 π ) * √39.4784176 / 2.0 kg

f₂ = 0.707 Hz

4 0

3 years ago

Miss Piggy is exercising her vocal chords by matching the frequency f = 686 Hz of her speaker 4 m away. Where should Kermit sit

monitta

Answer:

$z=\frac{2n+1}{8}$ for $n=0,1,2,3,...,15$

Where z=0 m is the position of Miss Piggy and z=4 m is the position of the speaker.

Explanation:

Assuming that Miss Piggy emits a sound wave that is in phase with the speaker, and that z=0 is the position of Miss Piggy and z=4 is the position of the speaker, we would have a superposition of two traveling sound waves. Furthermore let's assume that both waves have the same amplitude. The total resulting wave will be given by:

$\psi(t,z)=A\cos(\omega t-kz)+A\cos(\omega t +kz)$ where $\omega$ is the angular frequency of the traveling wave and $k$ is the wave number defined as $k=\frac{2\pi}{\lambda}$ . $\lambda$ is the wavelength of both traveling waves (they have the same wavelength because they have the same frequency). $\lambda=\frac{v}{f}$ where v is the speed of sound.