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4 years ago

Why does the air pressure inside a straw go down when you suck on the straw

2 answers:

7 0

A partial vacuum is created inside the straw. Gases exert pressure and when you take the gasses away (you sucking the air out of a straw) and it lowers the pressure inside of it.

Jobisdone [24]4 years ago

3 0

When you suck on the straw tou also suck in all the air and when the air comes out it brings the drink with it

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A heat engine (Power Cycle) with a thermal efficiency of 35 percent efficiency produces 750 kJ of work. Heat transfer to the eng

frosja888 [35]

Answer:

a) The schematic illustrating is attached

b) The heat transfer to the heat engine is 2142.86 kJ, the heat transfer from the heat engine is 1392.86 kJ

c) The heat transfer to the heat engine is 1648.35 kJ, the heat transfer from the heat engine is 898.35 kJ

Explanation:

b) The heat transfer to the engine and the heat transfer from the engine to the air is:

$Q_{1} =\frac{W}{n}$

Where

W = 750 kJ

n = 35% = 0.25

Replacing:

$Q_{1} =\frac{750}{0.35} =2142.86kJ$

$Q_{2} =Q_{1} -W=2142.86-750=1392.86kJ$

c) The efficiency of Carnot engine is:

$n=1-\frac{300K}{550K} =0.455$

The heat transfer to the heat engine is:

$Q_{1c} =\frac{750}{0.455} =1648.35kJ$

The heat transfer from the heat engine is:

$Q_{2c} =1648.35-750=898.35kJ$

4 0

3 years ago

Why is an increase in speed a curved line on a position vs. time graph but a straight diagonal line on a speed vs. time graph?

guapka [62]

What do you need help with

7 0

3 years ago

What is mean by the value of universal gravitional constant is 6.67×10^-11

aev [14]

Answer:

According to the gravitational law of Isaac Newton, "the gravitational force between any two objects is proportional to the product of the objects’ masses and inversely proportional to the square of the separation between their centers".

Therefore gravitational constant is the proportionality constant used in Newton’s Law of Universal Gravitation, and is commonly denoted by G. It is expressed as:

F= Gm1m2/r2

Another scientist Cavendish was able to measure the gravitational force and the value of the proportionality constant. It is expressed as G = 6.673×10-11 N m2 kg-2.

8 0

3 years ago

An ammeter is connected in series with a resistor of unknown resistance R and a DC power supply of known emf e. A student uses t

rosijanka [135]

Answer:

B:The actual power dissipated by the resistor is less than P because the ammeter had some resistance.

Explanation:

Here,power has been calculated using current I and total EMF \ε . So,P=EMF*current= ε I will represent total power dissipated in resistor and ammeter.

Now, this total power P has been dissipated in both resistor and ammeter. So, power dissipated in resistor must be less than P as some power is also dissipated in ammeter because it has non-zero resistance.

So, the answer is B:The actual power dissipated by the resistor is less than P because the ammeter had some resistance.

Note that option A,C and E are ruled out as they state power dissipated by resistor is greater than or equal to P which is false.

Also,option D is ruled out as ammeter is connected in series.

8 0

4 years ago

A parallel-plate capacitor has square plates that are 7.20 cm on each side and 3.40 mm apart. The space between the plates is co

Lilit [14]

Answer:

U = 218 nJ

Explanation:

We are given;

Spacing between the plates; d = 3.4 mm = 3.4 × 10^(-3) m

Voltage across the capacitor; V = 96 V

Dimension of the square plates is 7.2cm x 7.2cm.

So, Area = 7.2 × 7.2 = 51.84 cm² = 51.84 × 10^(-4) m²

Permittivity of free space; ε_o = 8.85 × 10^(-12) C²/N.m²

From relative permeability table;

Dielectric constant of Pyrex; k1 = 5.6

Dielectric constant of polystyrene; k2 = 2.56

Now, formula for capacitance of a capacitor with Dielectric is;

C = kC_o

Where, C_o = ε_o(A/d)

Since there are 2 capacitors, d will now be d/2 = (3.4 × 10^(-3))/2 m = 1.7 × 10^(-3)

Since we have 2 capacitor, thus ;

C1 = k1*ε_o*(A/d)

C1 = (5.6 × 8.85 × 10^(-12) × (51.84 × 10^(-4))/(1.7 × 10^(-3))

C1 = 1.51 × 10^(-10) F

Similarly;

C2 = (2.56 × 8.85 × 10^(-12) × (51.84 × 10^(-4))/(1.7 × 10^(-3))

C2 = 0.691 × 10^(-10) F

For capacitors in series, formula for total capacitance(Cs) is;

1/Cs = (1/C1) + (1/C2)

Simplifying this, we have;

Cs = (C1*C2)/(C1 + C2)

Plugging in the relevant values ;

Cs = (1.51 × 10^(-10)*0.691 × 10^(-10))/((1.51 × 10^(-10)) + (0.691 × 10^(-10)))

Cs = 0.474 × 10^(-10) F

The formula for energy stored in a capacitor with 2 Dielectrics is given as;

U = ½Cs*V²

So,

U = ½ × 0.474 × 10^(-10) × 96²

U = 2.18 × 10^(-7) J = 218 × 10^(-9) = 218 nJ

8 0

3 years ago