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kakasveta [241]

4 years ago

11

two truckers are traveling directly away from each other at the same speed. If one trucker sounds her horn at a frequency of 206

Hz, and the other trucker hears a frequency of 189 Hz, determine the speed of the trucks. Use the speed of sound as 343 m/s. m/s

1 answer:

boyakko [2]4 years ago

3 0

Answer:

v' = 14.76 m/s

Explanation:

given,

frequency of the one truck = 206 Hz

apparent frequency ,f' = 189 Hz

speed of sound, v = 343 m/s

speed of observer (v_o)and source (v_s) = v'

now, using Doppler's effect

$f' = \dfrac{v-v_o}{v+v_s}\ f$

$f' = \dfrac{v- v'}{v+v'}\ f$

$189 = \dfrac{343- v'}{343+v'}\ 206$

$0.9174= \dfrac{343- v'}{343+v'}$

314.69 + 0.9174 v' = 343 - v'

1.9174 v' = 28.30

v' = 14.76 m/s

hence, the speed of the truck is equal to 14.76 m/s

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A sled of mass 2.12 kg has an initial speed of 5.49 m/s across a horizontal surface. The coefficient of kinetic friction between

Darya [45]

Answer:

The speed of the sled is 3.56 m/s

Explanation:

Given that,

Mass = 2.12 kg

Initial speed = 5.49 m/s

Coefficient of kinetic friction = 0.229

Distance = 3.89 m

We need to calculate the acceleration of sled

Using formula of acceleration

$a = \dfrac{F}{m}$

Where, F = frictional force

m = mass

Put the value into the formula

$a=\dfrac{\mu mg}{m}$

$a=\mu g$

$a=0.229\times9.8$

$a=2.244\ m/s^2$

We need to calculate the speed of the sled

Using equation of motion

$v^2=u^2-2as$

Where, v = final velocity

u = initial velocity

a = acceleration

s = distance

Put the value in the equation

$v ^2=(5.49)^2-2\times2.244\times3.89$

$v=\sqrt{(5.49)^2-2\times2.244\times3.89}$

$v=3.56\ m/s$

Hence, The speed of the sled is 3.56 m/s.

8 0

3 years ago

A transverse wave is traveling through a canal. If the distance between two successive crests is 3.17 m and four crests of the w

Thepotemich [5.8K]

Answer:

a. 0.18Hz

b. 0.56m/s

Explanation:

From the question we can deduct the following parameters

The wavelength, λ is define as the distance between two successful crest or trough and from the question we conclude that wavelength is 3.17m.

Also the period of the wave T can be computed as

T=22.6/4

T=5.65secs.

a. To compute the frequency, recall that frequency, F=1/period.

Hence,

F=1/5.65

F=0.18Hz

b. Next we compute the wave speed.

Wave speed=frequency *wavelength

Wave speed =0.18*3.17

Wave speed =0.56m/s

5 0

3 years ago

A uniform beam with mass M and length L is attached to the wall by a hinge, and supported by a cable. A mass of value 3M is susp

Jobisdone [24]

Answer:

The tension is $T= \frac{11}{2\sqrt{3} } Mg$

The horizontal force provided by hinge $Fx= \frac{11}{4\sqrt{3} } Mg$

Explanation:

From the question we are told that

The mass of the beam is $m_b =M$

The length of the beam is $l = L$

The hanging mass is $m_h = 3M$

The length of the hannging mass is $l_h = \frac{3}{4} l$

The angle the cable makes with the wall is $\theta = 60^o$

The free body diagram of this setup is shown on the first uploaded image

The force $F_x \ \ and \ \ F_y$ are the forces experienced by the beam due to the hinges

Looking at the diagram we ca see that the moment of the force about the fixed end of the beam along both the x-axis and the y- axis is zero

So

$\sum F =0$

Now about the x-axis the moment is

$F_x -T cos \theta = 0$

=> $F_x = Tcos \theta$

Substituting values

$F_x =T cos (60)$

$F_x= \frac{T}{2} ---(1)$

Now about the y-axis the moment is

$F_y + Tsin \theta = M *g + 3M *g ----(2)$

Now the torque on the system is zero because their is no rotation

So the torque above point 0 is

$M* g * \frac{L}{2} + 3M * g \frac{3L}{2} - T sin(60) * L = 0$

$\frac{Mg}{2} + \frac{9 Mg}{4} - T * \frac{\sqrt{3} }{2} = 0$

$\frac{2Mg + 9Mg}{4} = T * \frac{\sqrt{3} }{2}$

$T = \frac{11Mg}{4} * \frac{2}{\sqrt{3} }$

$T= \frac{11}{2\sqrt{3} } Mg$

The horizontal force provided by the hinge is

$F_x= \frac{T}{2} ---(1)$

Now substituting for T

$F_{x} = \frac{11}{2\sqrt{3} } * \frac{1}{2}$

$Fx= \frac{11}{4\sqrt{3} } Mg$

4 0

3 years ago

What is the answer to this question

scoundrel [369]

Answer: A

Explanation:

Molecules speed up as heat is added

For example when water is heated as the water gets hotter the molecules speed up causing the water to boil and change phases into a gas (this is called evaporation)

In an ice cube the water molecules are frozen (barely moving compressed tight together) as the ice cube heats up the molecules start speeding up and moving further apart as the ice cube turns into liquid form. So as heat is added molecules speed up, move faster and spread further apart

7 0

3 years ago

The difference in the average speed of two trains is 16 miles per hour. the slower train takes 2 hours longer to travel 170 mile

VikaD [51]

Lets assume that s is the speed of the slower train and f is the speed of the faster train.
s = f - 16
f = 150 / t
s = 170 / ( t+2 )
-----------------------
170 / ( t+2 ) = 150 / t - 16 / t * ( t + 2 )
170 t = 150 * ( t + 2 ) - 16 t * ( t + 2 )
170 t = 150 t + 300 - 16 t² - 32 t
16 f² + 52 t - 300 = 0 / : 4 ( We will divide both sides of the equation by 4 )
4 t² + 13 t - 75 = 0
t 1/2 = ( -13 + √(169 + 1200 ) )/ 8
t = ( - 13 + 37 ) / 8 = 24 / 8 = 3
t = 3 h
s = 170 : ( 3 + 2 ) = 170 : 5 = 34 mph
Answer: The speed of the slower train is 34 mph.

7 0

3 years ago