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2 years ago

Pls help. This is about heat. I got the answer, just need the working

Physics

1 answer:

Mars2501 [29]2 years ago

7 0

Answer:

See below

Explanation:

You have to heat the calorimeter to 100 C from 20 C

this will take .20 kg * 390 j /kg-C * 80 C = 6240 j

You have to heat the mass of water to boiling point (100 C ) from 20C

this will take

.50 kg * 4182 j/kg-C * 80 = 167,280 j

AND you have to add enough heat to boil off .03 kg of water:

.03 kg * (2260000 j/kg-C ) = 67,800 j

Power = joules / sec = (6240 + 167280 + 67800) / 274.8 = 878 watts

Your answer may differ just a bit for slightly different or rounded values of specific heat or heat of fusion for water .....

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The crest of one wave with an amplitude of 4 m meets up with the crest of a second

trapecia [35]

Answer:

Constructive

Explanation:

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3 years ago

The radioactive 60co isotope is used in nuclear medicine to treat certain types of cancer. Calculate the wavelength and frequenc

Ivanshal [37]

1. Frequency: $3.23\cdot 10^{20} Hz$

The energy given is the energy per mole of particles:

$E=1.29\cdot 10^{11} J/mol$

1 mole contains a number of Avogadro of particles, $N_A$ , equal to

$N_A=6.022\cdot 10^{23}$ particles

So, by setting the following proportion, we can calculate the energy of a single photon:

$1.29 \cdot 10^{11} J/mol : 6.022 \cdot 10^{23} ph/mol = E_1 : 1 ph\\E_1 = \frac{(1.29\cdot 10^{11} J/mol)(1 ph)}{6.022\cdot 10^{23} ph/mol}=2.14\cdot 10^{-13} J$

This is the energy of a single photon; now we can calculate its frequency by using the formula:

$E_1 = hf$

where

$h=6.63\cdot 10^{-34} Js$ is the Planck's constant

f is the photon frequency

Solving for f, we find

$f=\frac{E_1}{h}=\frac{2.14\cdot 10^{-13} J}{6.63\cdot 10^{-34} Js}=3.23\cdot 10^{20} Hz$

2. Wavelength: $9.29\cdot 10^{-13} m$

The wavelength of the photon is given by the equation:

$\lambda=\frac{c}{f}$

where

$c=3\cdot 10^8 m/s$

is the speed of the photon (the speed of light). Substituting,

$\lambda=\frac{3 \cdot 10^8 m/s}{3.23\cdot 10^{20} Hz}=9.29\cdot 10^{-13} m$

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3 years ago

What type of energy transformation is taking place when natural gas is used to heat water

bazaltina [42]

Thermal energy transformation is taking place.

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3 years ago

When an automobile moves with constant velocity, the power developed is used to overcome the frictional forces exerted by the ai

geniusboy [140]

Answer:

The total frictional force is 358.0 newtons

Explanation:

Power is the amount of average work (W) an object does on a period of time (Δt):

$P=\frac{W}{\Delta t}$

Remember average work is average force (F) times displacement (Δs):

$P=\frac{F \Delta s}{\Delta t}$

but displacement over time is average speed $v=\frac{\Delta s}{\Delta t}$ , then:

$P=Fv$ (1)

That is, the power of the car is the force the engine does times the speed of the car. As the question states, if the car is at constant velocity then the power developed is used to overcome the frictional forces exerted by the air and the road, that is by Newton's first law, the force the motor of the car does is equal the force of frictional forces. So, to find the frictional forces we only have to solve (1) for F:

$F=\frac{P}{v}$