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4 years ago

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An office worker uses an immersion heater to warm 250 g of water in a light, covered, insulated cup from 20°C to 100°C in 4.00 m

inutes. The heater is a Nichrome resistance wire connected to a 120-V power supply. Assume the wire is at 100°C throughout the 4.00-min time interval. Specify a diameter and a length the wire can have. Can it be made from less than 0.5 cm3 of Nichrome?

1 answer:

posledela4 years ago

3 0

The amount of energy needed to raise the temperature of 250 g of water from 20 to 100 degree Celsius is
Q = 250 (4.18) (100 - 20)
Q = 83600 J

The power delivered is
P = 83600 / (4(60))
P = 348.33 W

According to the data for a Nichrome wire, the wire gauge for power rating of 348.33 W and 120 V power supply is
23-27 AWG

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A key falls from a bridge that is 45 m above the water. the key falls straight down and lands in a model boat traveling at a con

erastova [34]

Let the key is free falling, therefore from equation of motion

$h = ut +\frac{1}{2}gt^2.$ .

Take initial velocity, u=0, so

$h = 0\times t + \frac{1}{2}g t^2= \frac{1}{2}gt^2$ .

$h = 0\times t + \frac{1}{2}g t^2= \frac{1}{2}gt^2 \\\ t =\sqrt{\frac{2h}{g} }$

As velocity moves with constant velocity of 3.5 m/s, therefore we can use formula

$d= v \times t$

From above substituting t,

$d = v \times \sqrt{\frac{2h}{g} }$ .

Now substituting all the given values and g = 9.8 m/s^2, we get

$d = 3.5 \ m/s \times \sqrt{\frac{2 \times 45 m}{9.8 m/s^2} } = 10.60 m$ .

Thus, the distance the boat was from the point of impact when the key was released is 10.60 m.

7 0

3 years ago

A steel wire of length 31.0 m and a copper wire of length 17.0 m, both with 1.00-mm diameters, are connected end to end and stre

Brut [27]

Answer:

The time taken is $t = 0.356 \ s$

Explanation:

From the question we are told that

The length of steel the wire is $l_1 = 31.0 \ m$

The length of the copper wire is $l_2 = 17.0 \ m$

The diameter of the wire is $d = 1.00 \ m = 1.0 *10^{-3} \ m$

The tension is $T = 122 \ N$

The time taken by the transverse wave to travel the length of the two wire is mathematically represented as

$t = t_s + t_c$

Where $t_s$ is the time taken to transverse the steel wire which is mathematically represented as

$t_s = l_1 * [ \sqrt{ \frac{\rho * \pi * d^2 }{ 4 * T} } ]$

here $\rho_s$ is the density of steel with a value $\rho_s = 8920 \ kg/m^3$

So

$t_s = 31 * [ \sqrt{ \frac{8920 * 3.142* (1*10^{-3})^2 }{ 4 * 122} } ]$

$t_s = 0.235 \ s$

And

$t_c$ is the time taken to transverse the copper wire which is mathematically represented as

$t_c = l_2 * [ \sqrt{ \frac{\rho_c * \pi * d^2 }{ 4 * T} } ]$

here $\rho_c$ is the density of steel with a value $\rho_s = 7860 \ kg/m^3$

So

$t_c = 17 * [ \sqrt{ \frac{7860 * 3.142* (1*10^{-3})^2 }{ 4 * 122} } ]$

$t_c =0.121$

So

$t = t_c + t_s$

$t = 0.121 + 0.235$

$t = 0.356 \ s$

4 0

3 years ago

A. How long (in ns) does it take light to travel 1.0 m in a vacuum?

suter [353]

Answer:

a) 3.33 ns

b) Water distance = 0.75 m

Glass distance = 0.66 m

Diamond distance = 0.41 m

Explanation:

We take the speed of light, c = m/s.

Speed = distance/time

Time = distance/speed

a)

$t=\dfrac{1}{3.0\times10^{8}}=3.33\times10^{-9}$

t = 3.33 ns

b)

Refractive index, n = speed of light in vacuum / speed of light in medium

$n=\dfrac{c}{s}$

$s=\dfrac{c}{n}$

$d=s\times t$

$d=\dfrac{c}{n}\times \dfrac{1}{c}$

$d=\dfrac{1}{n}$

Thus, the distance traveled in the same time is numerically equal to the reciprocal of the refractive index.

For water n = 1.333

d = 1/1.333 = 0.75 m

For glass n = 1.517

d = 0.66 m

For diamond n = 2.417

d = 0.41 m

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3 years ago

Radio wave radiation falls in the wavelength region of 10.0 to 1000 meters. What is the energy of radio wave radiation that has

dmitriy555 [2]

Answer:

Explanation:

Given

Wavelength of radiation $\lambda =784\ m$

We know Energy of wave with wavelength $\lambda$ is given by

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

where h=Planck's constant

c=velocity of light

$\lambda$ =wavelength of wave

$E=\frac{6.626\times 10^{-34}\times 3\times 10^8}{784}$

$E=2.53\times 10^{-28}\ J$

Hence the energy of the wave with wavelength 784 m is $2.53\times 10^{-28}\ J$

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3 years ago

Would tap water likely freeze and boil at those exact temperatures? (temperature freezes at 0 degree celius and boils at 100 deg

Kitty [74]

No

Explanation:

Tap water will not boil and freeze at those exact temperature which are the boiling and freezing points.

O°C and 100°C are the boiling points of pure water.

Pure water is a pure substance with a definite composition made up of 2 atoms of hydrogen and 1 atom of oxygen.

Pure water boils at 100°C and freezes at O°C ,

Tap water is not pure water.
It has some impurities in it which causes causes the elevation of the boiling point of liquids and widening of the boiling range.
Tap water is treated water that contains some other dissolved chemicals.

learn more:

Molecular formula brainly.com/question/4574324

#learnwithBrainly

6 0

3 years ago