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3 years ago

How does a thermostat know how to keep hot soup hot and cold soup cold?

1 answer:

3 0

A thermos keeps thing hot or cold by using vacuum technology to keep air from getting inside. The double walled feature of the cup is what allows the container to be "vacuum sealed". In manufacturing the air between the two walls is removed creating the seal. The lack of air keeps the heat or cold from transfering, therefore letting it remain basically the same temperature.

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Sara is riding her bike down the road at 35 km/hr. She starts to peddle faster as she

steposvetlana [31]

Answer:

Distance covered to top of the hill was : 1.755 km

Explanation:

Initial velocity = 35 km/hr

Acceleration = 2.0 km/hr²

Time taken to accelerate = 3 minutes = 3/60 hours = 1/20 hours

Formula for acceleration : a = Δv /t

v-u/t ---where u is initial velocity , v is final velocity and t is time taken for acceleration

v- 35 / 0.05 = 2

v = 35.10 km/h

Formula for distance is product of speed and time

Distance covered = 35.10 * 0.05 = 1.755 km

6 0

3 years ago

Different between group IA and IIA elements

Mekhanik [1.2K]

Answer:

Group IA elements have only one valency electron while Group IIA have two valency electrons.

Group IA elements have cations with higher charge density hence polarizing anions easier resulting into covalent character while Group IIA elements have cations with lower charge density hence difficulty in distorting anions resulting into a ionic character. This is due to difference in cationic radii and charges

8 0

2 years ago

Can someone help me with the motion maps, I don't understand what I am supposed to write in the description or how to draw the a

Ugo [173]

Answer:

i d k

Explanation:

7 0

2 years ago

An ideal gas is allowed to expand isothermally from 2.00 l at 5.00 atm in two steps:

Burka [1]

Heat added to the gas = Q = 743 Joules

Work done on the gas = W = -743 Joules

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<h3>Further explanation</h3>

The Ideal Gas Law that needs to be recalled is:

$\large {\boxed {PV = nRT} }$

<em>P = Pressure (Pa)</em>

<em>V = Volume (m³)</em>

<em>n = number of moles (moles)</em>

<em>R = Gas Constant (8.314 J/mol K)</em>

<em>T = Absolute Temperature (K)</em>

Let us now tackle the problem !

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<u>Given:</u>

Initial volume of the gas = V₁ = 2.00 L

Initial pressure of the gas = P₁ = 5.00 atm

<u>Unknown:</u>

Work done on the gas = W = ?

Heat added to the gas = Q = ?

<u>Solution:</u>

<em>Ideal gas is allowed to expand isothermally:</em>

$P_1V_1 = P_2V_2$

$5.00 \times 2.00 = 3.00 \times V_2$

$V_2 = 10 \div 3$

$V_2 = 3\frac{1}{3} \texttt{ L}$

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<em>Next we will calculate the work done on the gas:</em>

$W_A = -P_2(V_2 - V_1)$

$W_A = -3.00(3\frac{1}{3} - 2.00)$

$W_A = \boxed{-4 \texttt{ L.atm}}$

$\texttt{ }$

<em>Using the same method as above:</em>

$P_2V_2 = P_3V_3$

$3.00 \times 3\frac{1}{3} = 2.00 \times V_3$

$V_3 = 10 \div 2$

$V_3 = 5 \texttt{ L}$

$\texttt{ }$

<em>Next we will calculate the work done on the gas:</em>

$W_B = -P_3(V_3 - V_2)$

$W_B = -2.00(5 - 3\frac{1}{3})$

$W_B = \boxed{-3\frac{1}{3} \texttt{ L.atm}}$

$\texttt{ }$

<em>Finally we could calculate the total work done and heat added as follows:</em>

$W = W_A + W_B$

$W = -4 + (-3\frac{1}{3})$

$W = -7\frac{1}{3} \texttt{ L.atm}$

$W = -7\frac{1}{3} \times 101.33 \texttt{ J}$

$\boxed{W \approx -743 \textt{ J}}$

$\texttt{ }$

$\Delta U = Q + W$

$0 = Q + (-743)$

$\boxed{Q = 743 \texttt{ J}}$

$\texttt{ }$

<h3>Learn more</h3>

Minimum Coefficient of Static Friction : brainly.com/question/5884009
The Pressure In A Sealed Plastic Container : brainly.com/question/10209135
Effect of Earth’s Gravity on Objects : brainly.com/question/8844454

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<h3>Answer details</h3>

Grade: High School

Subject: Physics

Chapter: Pressure

5 0

3 years ago

Jazz is a 172 lb athlete who exercised at 7.6 METs. At this workload, what is his energy expenditure in kcals/min.? Round to the

dezoksy [38]

Answer:

Energy expenditure in K cals/min = 10 K cals /min (approximately)

Explanation:

As we know

Energy expenditure in Kcal/min= METs x 3.5 x Body weight (kg) / 200

Given is METs=7.6

Weight of Jazz= 172lb=78.02kg

putting the values in formula,

Energy expenditure in K cals/min= 7.6 x 3.5 x 78.02 / 200

=10.38 K cals /min

=10 K cals /min (approximately)

Therefore, Energy expenditure in K cals/min by Jazz will be approximately 10 K cals /min

8 0

3 years ago