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gizmo_the_mogwai [7]
3 years ago
11

4 This question has several parts that must be completed sequentially. If you skip a part of the question, you will not receive

any points for the skipped part, and you will not be able to come back to the skipped part. Tutorial ExerciseA boat leaves a dock at 8:00 PM and travels due south at a speed of 20 km/h. Another boat has been heading due east at 15 km/h and reaches the same dock at 9:00 PM How many minutes after 8:00 PM were the two boats closest together
Physics
1 answer:
zubka84 [21]3 years ago
3 0

Answer:at 21.6 min they were separated by 12 km

Explanation:

We can consider the next diagram

B2------15km/h------->Dock

|

|

B1 at 20km/h

|

|

V

So by the time B1 leaves, being B2 traveling at constant 15km/h and getting to the dock one hour later means it was at 15km from the dock, the other boat, B1 is at a distance at a given time, considering constant speed of 20km/h*t going south, where t is in hours, meanwhile from the dock the B2 is at a distance of (15km-15km/h*t), t=0, when it is 8pm.

Then we have a right triangle and the distance from boat B1 to boat B2, can be measured as the square root of (15-15*t)^2 +(20*t)^2. We are looking for a minimum, then we have to find the derivative with respect to t. This is 5*(25*t-9)/(sqrt(25*t^2-18*t+9)), this derivative is zero at t=9/25=0,36 h = 21.6 min, now to be sure it is a minimum we apply the second derivative criteria that states that if the second derivative at the given critical point is positive it means here we have a minimum, and by calculating the second derivative we find it is 720/(25 t^2 - 18 t + 9)^(3/2) that is positive at t=9/25, then we have our answer. And besides replacing the value of t we get the distance is 12 km.

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Human activities can have positive and negative effects on the environment. Humans can benefit natural areas by
svp [43]
The answer would be D , the rest are ways humans basically destroy nature
4 0
4 years ago
If for a given pair of media CR
nika2105 [10]

CR​ < CY​ < CB​

<h3>Which factors affect the critical angle for a given pair of media?</h3>

The factors which affect the critical angle are

(a) The colour (or wavelength) of light

(b) The temperature

(i) Effect of colour of light: The critical angle for a pair of media is less for the violet light and more for the red light. Thus the critical angle increases with the increase in wavelength of light.

(ii) Effect of temperature: The critical angle increases with increase in temperature because on increasing temperature of medium, its refractive index decreases.

According to the question,

μ 1​ sinCR​ =1

μ 2​ sinCY =1

μ 3​ sinCB​ =1

μ 1​ > μ 2​  and μ 2​ > μ 3

⟹μ 1​ > μ 2​ > μ 3

CR​ < CY​ < CB​

Thus,

The critical angle increases with the increase in wavelength of light.

Learn more about wavelength of light here:

brainly.com/question/27557868

#SPJ1

7 0
2 years ago
Unless indicated otherwise, assume the speed of sound in air to be v = 344 m/s.A violinist is tuning her instrument to concert A
Molodets [167]

Answer:

A) 443 Hz

B) She has to loosen the string

Explanation:

A) Given;

Beat frequency;f_beat = 3 Hz

Frequency of electronically generated tone; f_e = 440 Hz

We know that formula for beat frequency is given by;

f_beat = |f1 - f2|

Now, applying it to this question, we have;

f_beat = f_v - f_e

Where f_v is frequency of the note played by the violinist

Thus, plugging in the relevant values;

3 = f_v - 440

f_v = 3 + 440

f_v = 443 Hz

B) In the concept of wave travelling in a string, the frequency is directly proportional to the square root of the force acting on the string.

Now, for the violinist to get her violin perfectly tuned to concert A from what it was when she heard the 3-Hz beats, the beat frequency will have to be zero. Which means it has to decrease by 3 Hz. For it to decrease, it means that the force applied has to decrease as we have seen that frequency is directly proportional to the square root of the force acting on the string.

Thus, she would have to loosen the string.

7 0
4 years ago
How much force is required to hold an empty carton of volume 1.5 L beneath the surface in a sink of water? Assume the carton is
Gwar [14]

Answer:

It will require 14.715 N of force to hold the cartoon beneath the water.

Explanation:

Given the the volume of cartoon is 1.5 liters.

We need to find the force required to hold this cartoon beneath the water.

As we know from the Archimedes principle that the net force is equal to the volume of liquid displaced.

Given volume of the cartoon is 1.5 liters. So, 1.5 liters of water will be displaced.

And we know the density of the water is 1000\ kg/m^3. That is 1\ kg/L

And g=9.81\ m/s^2

F_N=\rho Vg\\F_N=1\times 1.5\times 9.81\\F_N=14.715\ N

So, it will require 14.715 N of force to hold 1.5 liter volume of cartoon beneath the water.

6 0
3 years ago
The water stream strikes the inclined surface of the cart. Determine the power produced by the stream if, due to rolling frictio
levacccp [35]

Answer

given,

constant speed of cart on right side = 2 m/s

diameter of nozzle = 50 mm = 0.05 m

discharge flow through nozzle = 0.04 m³

One-fourth of the discharge flows down the incline

three-fourths flows up the incline

Power = ?

Normal force i.e. Fn acting on the cart

F_n = \rho A (v - u)^2 sin \theta

v is the velocity of jet

Q = A V

v = \dfrac{0.04}{\dfrac{\pi}{4}d^2}

v= \dfrac{0.04}{\dfrac{\pi}{4}\times 0.05^2}

v = 20.37 m/s

u be the speed of cart assuming it to be u = 2 m/s

angle angle of inclination be 60°

now,

F_n = 1000 \times \dfrac{\pi}{4}\times 0.05^2\times (20.37 - 2)^2 sin 60^0

F n = 2295 N

now force along x direction

F_x = F_n sin 60^0

F_x = 2295 \times sin 60^0

F_x = 1987.52\ N

Power of the cart

P = F x v

P = 1987.52 x 20.37

P = 40485 watt

P = 40.5 kW

3 0
4 years ago
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