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2 years ago

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Physical therapists know as you soak tired muscles in a hot tub, the water will cool down as you heat up. If a 67.9 kg person at

37.1 oC immerses in 50.2 kg of water at 40.5o C, the equilibrium temperature is 38.7 oC.
What is the specific heat of the person?
Use 4.186 kJ/kgoC for the specific heat of water.

1 answer:

Lubov Fominskaja [6]2 years ago

4 0

Answer:

c = 5032.8J/kg°C

Explanation:

the transfer of heat is given by

$Q_1=-Q_2\\\\Q=cm(T_f-T_i)$

c is the specific heat, m the mass and T the temperatures at equilibrium an at the beginning.

By replacing we obtain

$c_1m_1(T_f-T_{1i})=-c_2m_2(T_f-T_{2i})\\\\c_2=-\frac{c_1m_1(T_f-T_{1i})}{m_2(T_f-T_{2i})}=-\frac{(67.9kg)(4186J/kg\°C)(38.7\°C-37.1\°C)}{(50.2kg)(38.7\°C-40.5\°C)}\\\\c_2=5032.8\frac{J}{kg\°C}$

hope this helps!!

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When was the first electric typewriter produced and by what company

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In 1920, after returning from Army service, he produced a successful model and in 1923 turned it over to the Northeast Electric Company of Rochester for development.

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3 years ago

Two kids are playing on a newly installed slide, which is 3 m long. John, whose mass is 30 kg, slides down into William (20 kg),

yuradex [85]

Answer:

$v=3.564\ m.s^{-1}$

$\Delta v =2.16\ m.s^{-1}$

Explanation:

Given:

mass of John, $m_J=30\ kg$

mass of William, $m_W=30\ kg$

length of slide, $l=3\ m$

(A)

height between John and William, $h=1.8\ m$

<u>Using the equation of motion:</u>

$v_J^2=u_J^2+2 (g.sin\theta).l$

where:

v_J = final velocity of John at the end of the slide

u_J = initial velocity of John at the top of the slide = 0

Now putting respective :

$v_J^2=0^2+2\times (9.8\times \frac{1.8}{3})\times 3$

$v_J=5.94\ m.s^{-1}$

<u>Now using the law of conservation of momentum at the bottom of the slide:</u>

<em>Sum of initial momentum of kids before & after collision must be equal.</em>

$m_J.v_J+m_w.v_w=(m_J+m_w).v$

where: v = velocity with which they move together after collision

$30\times 5.94+0=(30+20)v$

$v=3.564\ m.s^{-1}$ is the velocity with which they leave the slide.

(B)

frictional force due to mud, $f=105\ N$

<u>Now we find the force along the slide due to the body weight:</u>

$F=m_J.g.sin\theta$

$F=30\times 9.8\times \frac{1.8}{3}$

$F=176.4\ N$

<em><u>Hence the net force along the slide:</u></em>

$F_R=71.4\ N$

<em>Now the acceleration of John:</em>

$a_j=\frac{F_R}{m_J}$

$a_j=\frac{71.4}{30}$

$a_j=2.38\ m.s^{-2}$

<u>Now the new velocity:</u>

$v_J_n^2=u_J^2+2.(a_j).l$

$v_J_n^2=0^2+2\times 2.38\times 3$

$v_J_n=3.78\ m.s^{-1}$

Hence the new velocity is slower by

$\Delta v =(v_J-v_J_n)$

$\Delta v =5.94-3.78= 2.16\ m.s^{-1}$

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3 years ago

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Answer:

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Explanation:

We are going to answer the three questions

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3) when white light hits a prism it is refracted with the equation

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where the incidence of refraction depends on the wavelength, therefore for each color there is a different index of refraction and consequently the light is separated in its different colors.

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Why does it takes the outer planets so long to orbit the Sun? Try to come up with two reasons.

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well they are normally bigger than the inner planets, and they also have a bigger distance to go

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3 years ago

One molecule of bromine (Br2) and two molecules of potassium chloride (KCI) combine in a reaction. How many atoms are in the pro

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In the reaction between 1 molecule of bromine and 2 molecules of potassium chloride, there are six atoms in the products.

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We obtain as products, 2 molecules of potassium bromide and 1 molecule of chlorine.

1 molecule of KBr has 2 atoms, so 2 molecules contribute with 4 atoms.
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The 4 atoms from KBr and the 2 atoms from Cl₂ make a total of 6 atoms.

In the reaction between 1 molecule of bromine and 2 molecules of potassium chloride, there are six atoms in the products.

Learn more: brainly.com/question/21850455

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2 years ago

Read 2 more answers