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Elina [12.6K]
3 years ago
9

Just about everyone at one time or another has been burned by hot water or steam. This problem compares the heat input to your s

kin from steam as opposed to hot water at the same temperature.
Assume that water and steam, initially at 100?C, are cooled down to skin temperature, 34?C, when they come in contact with your skin. Assume that the steam condenses extremely fast. We will further assume a constant specific heat capacity c=4190J/(kg?K) for both liquid water and steam.

How much heat H1 is transferred to the skin by 25.0 g of steam onto the skin? The latent heat of vaporization for steam is L=2.256
Physics
1 answer:
Firlakuza [10]3 years ago
8 0

Answer:

63.3 KJ

Explanation:

Quantity of heat lost to the skin = mLw + mcΔT

where is mass in kg, Lw is latent heat of vaporization in KJ/kg ( 2.256 × 10^6 KJ/Kg), c is specific heat capacity of water (4190 J/(Kg.K) and ΔT is the change in temperature

m = 25g = 25 /1000 = 0.025 kg

quantity of heat loss = (0.025 × 2.256 × 10^6) +  ( 0.025 × 4190 × (100 -34 )

Quantity of heat loss to the skin = (5.64 × 10^4) + 5530.8 = 56400 + 6913.5 = 63313.5 = 63.3 KJ

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Researchers in the Antarctic measure the temperature to be -32°F. What is this temperature on the following scales?(a) the Celsi
Illusion [34]
Answer:

a) -35.6°C

b) 237.4 K

Explanation:

To convert temperature from degree celsius to degree fahrenheit, use the formula below:

T_c=\frac{5}{9}(T_f-32)

a) Therefore to convert -32°F to celsius, substitute it into the celsius

\begin{gathered} T_c=\frac{5}{9}(-32-32) \\  \\ T_c=\frac{5}{9}(-64) \\  \\ T_c=-35.6^0C \end{gathered}

b) To covert to the Kelvin scale, use the formula below

\begin{gathered} T_k=T_c+273 \\  \\ T_k=-35.6+273 \\  \\ T_k=237.4K \\  \end{gathered}

8 0
1 year ago
What is the melting point of substance A?
Misha Larkins [42]

Answer:

Solids are easily recognized by their ability to retain a fixed shape and definite volume. Particles making

up a solid are held together in a rigid form. They are not free to move about or slide past one another and

the solid does not have the ability to flow. (Although the particles of a solid do not move position to position, they do have motion in that they are constantly vibrating.

To change the temperature of a solid, heat energy must be added. The amount of heat energy that changes

the temperature of 1.0 g of a solid by 1.0°C is called its specific heat (c). Each substance has its own

specific heat. The specific heat of ice is 2.1 Joules/g°C. In other words we must supply 1.0 gram of ice

with 2.1 Joules of heat energy to raise its temperature by 1.0 °C.

The general equation for calculating heat energy to change the temperature of a solid is:

Heat = Mass x Specific Heat (solid) x Temperature Change

Q = m c DT

10 g 10 g 10 g 10 g 10 g 10 g

Calculate the heat necessary to change 10 g of ice(s) at -20 °C to 10 g of ice(s) at 0°C. (A-B)

Q = mc∆T = (10 g) (2.1 J/g°C) (20°C) = 420 J

If you continue to add heat energy once the temperature of the ice reaches 0°C , the heat absorbed is called

the heat of fusion (Lf). This heat is used to cause a change of phase (from a solid to a liquid). This heat is

increasing the potential energy of the molecules of the solid. No temperature change takes place. Each

substance has its own heat of fusion. The heat of fusion for ice is 340 Joules/g. Exactly the same amount

of heat is given up when 1.0 g of water is changed to ice. This heat is called the heat of crystallization.

The general equation for calculating heat energy to change a solid to a liquid is:

Heat = Mass x Heat of Fusion

Q = m Lf

Calculate the heat necessary to change 10 g of ice(s) at 0°C to 10 g of water(l) at 0°C.(B-C)

Explanation:

Q = mLf = (10 g)( 340 J/g) = 3400 J

3 0
3 years ago
A motorcycle starts from rest and has a constant acceleration. In a time interval t, it undergoes a displacement x and attains a
iren [92.7K]

Answer:

√(6ax)

Explanation:

Hi!

The question states that during a time t the motorcyle underwent a displacement x at constant acceleration a starting from rest, mathematically we can express it as:

x=(1/2)at^2

Then the we need to find the time t' for which the displacement is 3x

3x=(1/2)a(t')^2

Solving for t':

t'=√(6x/a)

Now, the velocity of the motorcycle as a function of time is:

v(t)=a*t

Evaluating at t=t'

v(t')=a*√(6x/a)=√(6*x*a)

Which is the final velocity

Have a nice day!

3 0
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A copper wire 20 m long and 4mm in diameter is attached to the Ceiling and a 400 N
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Answer:

A

Explanation:

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2 years ago
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The answer is 5 km/hr

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