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3 years ago

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A heart defibrillator is used to enable the heart to start beating if it has stopped. This is done by passing a large current of

12 A through the body at 25 V for a very short time, usually about 3.0 ms. (a) What power does the defibrillator deliver to the body, and (b) how much energy is transferred

1 answer:

Inessa [10]3 years ago

4 0

Answer:

(a) 300 W

(b)0.90 J

Explanation:

(a) The electric power for any circuit element is given as

$P=IV$

Here I is current passing in the circuit and V is the voltage.

Given I = 12 A and V =25 V.

Substitute the given values, we get

$P=12 A \times25 V$

P = 300 W.

Thus, the power defibrillator deliver to the body is 300 W.

(b) To calculate the electric energy use the relation between electric energy, power and time as

$E=Pt$

Given t = 3 ms.

Substitute the values, we get

$E=300 W\times 3\times 10^-^3s$

E = 0.90 J.

Thus, the energy transferred is 0.90 J.

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A modern compact fluorescent lamp contains 1.4 mg of mercury (Hg). If each mercury atom in the lamp were to emit a single photon

Reika [66]

Answer:

A. 1.64 J

Explanation:

First of all, we need to find how many moles correspond to 1.4 mg of mercury. We have:

$n=\frac{m}{M_m}$

where

n is the number of moles

m = 1.4 mg = 0.0014 g is the mass of mercury

Mm = 200.6 g/mol is the molar mass of mercury

Substituting, we find

$n=\frac{0.0014 g}{200.6 g/mol}=7.0\cdot 10^{-6} mol$

Now we have to find the number of atoms contained in this sample of mercury, which is given by:

$N=n N_A$

where

n is the number of moles

$N_A=6.022\cdot 10^{23} mol^{-1}$ is the Avogadro number

Substituting,

$N=(7.0\cdot 10^{-6} mol)(6.022\cdot 10^{23} mol^{-1})=4.22\cdot 10^{18}$ atoms

The energy emitted by each atom (the energy of one photon) is

$E_1 = \frac{hc}{\lambda}$

where

h is the Planck constant

c is the speed of light

$\lambda=508 nm=5.08\cdot 10^{-7}nm$ is the wavelength

Substituting,

$E_1 = \frac{(6.63\cdot 10^{-34} Js)(3\cdot 10^8 m/s)}{5.08\cdot 10^{-7} m}=3.92\cdot 10^{-19} J$

And so, the total energy emitted by the sample is

$E=nE_1 = (4.22\cdot 10^{18} )(3.92\cdot 10^{-19}J)=1.64 J$

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3 years ago

An object is lifted from the surface of aspherical planet to an altitude equal to the radius of the planet.As a result, what hap

serg [7]

An object is lifted from the surface of a spherical planet to an altitude equal to the radius of the planet.

As a result, the object's <em>mass remains the same</em>, and its <em>weight decreases</em> to 1/4 of whatever it is when the object is on the planet's surface.

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3 years ago

A stationary boat in the ocean is experiencing waves from a storm. The waves move at 59 km/h and have a wavelength of 145 m . Th

krek1111 [17]

Answer:

The time elapses until the boat is first at the trough of a wave is 4.46 seconds.

Explanation:

Speed of the wave, v = 59 km/h = 16.38 m/s

Wavelength of the wave, $\lambda=145\ m$

If f is the frequency of the wave. The frequency of a wave is given by :

$v=f\lambda\\\\f=\dfrac{v}{\lambda}\\\\f=\dfrac{16.38\ m/s}{145\ m}\\\\f=0.112\ Hz$

The time period of the wave is given by :

$T=\dfrac{1}{f}\\\\T=\dfrac{1}{0.112\ Hz}\\\\T=8.92\ s$

We need to find the time elapses until the boat is first at the trough of a wave. So, the time will be half of the time period of the wave.

$T=\dfrac{8.92}{2}\\\\T=4.46\ s$

Hence, this is the required solution.

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3 years ago

A mass m is attached to a string connected to a force sensor on a rotating platform. The platform’s angular velocity, ω, can be

makkiz [27]

Answer:

The mass m is 0.332 kg or 332 gm

Explanation:

Given

The platform is rotating with angular speed , $\omega =8.5\, \frac{rad}{sec}$

Mass m is moving on platform in a circle with radius , $r=0.20\, m$

Force sensor reading to which spring is attached , $F=4.8\, N$

Now for the mass m to move in circle the required centripetal force is given by $F=m\omega ^{2}r$

=> $4.8=m\times 8.5 ^{2}\times 0.20$

$=>m=0.332\, kg$

Thus the mass m is 0.332 kg or 332 gm

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3 years ago

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Answer:

The image is real.

The image is inverted.

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Explanation:

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3 years ago

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