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Ket [755]
3 years ago
11

A ship's boiler steam comes out at 112 C and pushes through the system, exiting into the condenser,

Physics
1 answer:
solniwko [45]3 years ago
5 0

Answer:

D: 0.239

Explanation:

Equation for ideal efficiency is;

η = 1 - (T_c/T_h)

We are told that;

steam comes out at 112° C. Thus, T_h = 112°C. Converting to Kelvin gives; T_h = 112 + 273 = 385 K

The one exiting into the condenser is kept at 20°C. Thus; T_c = 20 + 273 = 293 K

Thus;

η = 1 - (293/385)

η = 0.239

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A balloon of mass M is floating motionless in the air. A person of mass less than M is on a rope ladder hanging from the balloon
Tasya [4]

Let the mass of the person be m. Total momentum is conserved (because the exterior forces on the system are balanced), especially the component in the vertical direction.

Given that,

Mass of gallon is M

Let man mass be m

Velocity of man is v

Let velocity if ballot be Vb

When the person begin to move we have

Conservation of momentum

mv + MVb=0

MVb=-mv

Vb= -(m/M) v

Given that the mass of man is less than mass of balloon. i.e. m<M

So, if m<M, then, m/M <1

Therefore, .

Vb= -(m/M) v

Vb< -v

This implies that the velocity of balloon is less than the velocity of man and if is also moving in opposite direction

So the man is moving upward, then the balloon is moving downward and it's velocity is less than the velocity of man,

The answer is C

Down with a speed less than v

6 0
3 years ago
Read 2 more answers
A baseball pitcher throws the ball towards the batter at 90 mph. His bat connects with the ball for a line drive, after which th
forsale [732]

Answer:

F=-18412.9N, where the minus indicates the direction is opposite to that of the throw.

Explanation:

a)

Since MKS stands for meter-kilogram-second and we know that:

1\ hour = 3600\ seconds

1\ mile = 1600\ meters

1000g = 1kg

We can write that:

\frac{1\ hour}{3600\ seconds}=1

\frac{1600\ meters}{1\ mile}=1

\frac{1kg}{1000g}=1

These are conversion factors, equal to 1, so multiplying our results by them won't change their value, only their units.

So we have that:

90 mph=90 \frac{miles}{hour}(\frac{1\ hour}{3600\ seconds})(\frac{1600\ meters}{1\ mile})=40m/s

110 mph=110 \frac{miles}{hour}(\frac{1\ hour}{3600\ seconds})(\frac{1600\ meters}{1\ mile})=48.89m/s

145 g=145 g(\frac{1kg}{1000g})=0.145kg

b)

Newton's 2nd Law tells us that F=ma, and the definition of acceleration is a=\frac{\Delta v}{\Delta t}, so we have:

F=m\frac{\Delta v}{\Delta t}=m\frac{v_f-v_i}{t}

Taking the throw direction as the positive one, for our values we have:

F=m\frac{v_f-v_i}{t}=(0.145kg)\frac{(-48.89m/s)-(+40m/s)}{0.0007s}=-18412.9N

4 0
3 years ago
The mean time between collisions for electrons in room temperature copper is 2.5 x 10-14 s. What is the electron current in a 2
Darya [45]

Answer:

1.87 A

Explanation:

τ = mean time between collisions for electrons = 2.5 x 10⁻¹⁴ s

d = diameter of copper wire = 2 mm = 2 x 10⁻³ m

Area of cross-section of copper wire is given as

A = (0.25) πd²

A = (0.25) (3.14) (2 x 10⁻³)²

A = 3.14 x 10⁻⁶ m²

E = magnitude of electric field = 0.01 V/m

e = magnitude of charge on electron = 1.6 x 10⁻¹⁹ C

m = mass of electron = 9.1 x 10⁻³¹ kg

n = number density of free electrons in copper = 8.47 x 10²² cm⁻³ = 8.47 x 10²⁸ m⁻³

i = magnitude of current

magnitude of current is given as

i = \frac{Ane^{2}\tau E}{m}

i = \frac{(3.14\times 10^{-6})(8.47\times 10^{28})(1.6\times 10^{-19})^{2}(2.5\times 10^{-14}) (0.01)}{(9.1\times 10^{-31})}

i  = 1.87 A

4 0
3 years ago
A(n) _______ studies physical components and characteristics of celestial objects.
inna [77]

Answer:

Astronomers?

Explanation:

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2 years ago
Which substance will cool down the slowest during the night, and why?
Studentka2010 [4]

Cool down the Slowest

B. Seawater, because it heats up slower and gives away heat slower than sand.

Read the question wrong the first time

5 0
3 years ago
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