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oksian1 [2.3K]
2 years ago
6

A boat traveling across a river has a resultant velocity of 10 km/h and travels 34 degrees with respect to the shore. A) What is

the boats velocity in m/s?
B) What is the velocity of the river in m/s?
Physics
1 answer:
vodka [1.7K]2 years ago
6 0

Answer:

a) 1.55 m/s

b) 2.3 m/s

Explanation:

We know that the boat travels across the river, if we define the river as the x-axis, then the velocity of the boat is only on the y-axis.

Then we can write the velocity of the boat in still water as:

S = (0, B)

Now, when the boat is on the river, the velocity of the boat will be equal to the velocity of the boat in still water plus the velocity of the river.

The velocity of the river is:

v = (R, 0).

Then the velocity of the boat in that river is:

V' = (0, B) + (R, 0) = (R, B)

Now, we know that the velocity of the boat is 10km/h, and it travels at an angle of 34° with respect to the shore.

We can use the Pythagoreans theorem to write the components of this velocity as:

x-axis component = 10km/h*cos(34°) = 8.29 km/h

y-axis component = 10km/h*sin(34°) =  5.59 km/h

Then the velocity of the boat can be written in components as:

velocity = ( 8.29 km/h,  5.59 km/h)

And we knew that the velocity of the boat was written as  (R, B)

Then we must have:

R = 8.29 km/h

B = 5.59 km/h

a) The speed of the boat in m/s:

We know that the speed of the boat is 5.59 km/h.

First, we know that:

1km = 1000m, then:

5.59 km/h = 5.59*(1000m)h = 5,590 m/h

And we know that:

1h = 3600s

Then we can write:

5,590 m/h = 5,590 m/(3600s) = 1.55 m/s

b) The speed of the river in m/s:

We know that the speed of the river is 8.29 km/h

Using the same reasoning as above, we can do the change of units as follows:

8.29 km/h = 8.29 (1000m)/(3600s) = 2.3 m/s

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Answer:

4.95\cdot 10^{-21} J

Explanation:

First of all, let's convert everything into SI units:

n = 2.4 mol (number of gas moles)

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V=4.3 L=4.3\cdot 10^{-3} m^3 (gas volume)

R = 8.31451 J/K · mol (gas constant)

The ideal gas equation states that

pV=nRT

Solving for T, we find the gas temperature

T=\frac{pV}{nR}=\frac{(1.11\cdot 10^6)(4.3\cdot 10^{-3})}{(2.4)(8.31451)}=239.2 K

And now we can find the average kinetic energy of the gas:

E_K = \frac{3}{2}kT

where

k = 1.38066 × 10−23 J/K is the Boltzmann's constant

Substituting,

E_K = \frac{3}{2}(1.38066\cdot 10^{-23} J/K)(239.2 K)=4.95\cdot 10^{-21} J

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A washing machine heats 10kg of water in each wash cycle. How much energy is saved by washing at 30'c instead of 50'c if the sta
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The equation for this is very simple you add then you subtract then you get the answer then you divide then it all works out for you
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Photons with the highest energy have the ____
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Answer:

D. shortest wavelength

Explanation:

Photons with the highest energy have the shortest wavelength. The shorter the wavelength, the higher the energy of a photon.

A photon is a quantity that transmits electromagnetic energy from one place to the other.

  • Gamma rays have photons that transmits the highest amount of energy.
  • The rays have the shortest wavelength and highest frequency of all electromagnetic radiations.

Energy, wavelength and frequency of a photon are connected using the expression:

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Study the following reaction carefully. What classification should this reaction have?
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Answer:

Synthesis reaction

Explanation:

Synthesis reaction: two or more compounds combine to form one.

A + B → C

Decomposition reaction: one compound forms two or more.

C → A + B

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AB + C → AC + B

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6 0
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Elemental analysis of the unknown gas from part a revealed that it is 30.45% n and 69.55% o by mass. What is the molecular formu
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Answer:

the molecular formula for the gas is NO₂

Explanation:

since it contains

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Oxygen = o → 69.55%

and 30.45%+69.55% = 100% , then the gas only contains nitrogen and oxygen

Also we know that the proportion of oxygen over nitrogen  is

proportion of oxygen over nitrogen  = moles of oxygen / moles of nitrogen

since

moles = mass / molecular weight

then for a sample of 100 gr of the unknown gas

mass of oxygen = 69.55%*100 gr = 69.55 gr

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proportion of oxygen over nitrogen = (mass of oxygen/ molecular weight)/(mass of nitrogen / molecular weight of nitrogen ) =  (69.55 gr/ 16 gr/mol) /( 30.45 gr /14 gr/mol) = 1.998 mol of O/ mol of N≈ 2 mol of O/ mol of N

therefore there are 2 atoms of oxygen per atom of nitrogen

thus the molecular formula for the gas is:

NO₂

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