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3 years ago

If the frequency of wave is 400 Hz and its

Physics

1 answer:

agasfer [191]3 years ago

8 0

Answer:

D) 1000 m/s

Explanation:

$wavelength = \frac{velocity}{frequency}$

You have the wavelength and frequency, you just need to solve for velocity. You can do this by multiplying each side of the equation by frequency.

Hope this helps.

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If two objects A and B have the same kinetic energy but A has three times the momentum of B, what is the ratio of their inertias

Thepotemich [5.8K]

Answer:

$\frac{inertia_B}{inertia_A}=9$

Explanation:

First of all, let's remind that:

- The kinetic energy of an object is given by $K=\frac{1}{2}mv^2$ , where m is the mass and v is the speed

- The momentum of an object is given by $p=mv$

- The inertia of an object is proportional to its mass, so we can write $I=km$ , where k just indicates a constant of proportionality

In this problem, we have:

- $K_A = K_B$ (the two objects have same kinetic energy)

- $p_A = 3 p_B$ (A has three times the momentum of B)

Re-writing both equation we have:

$\frac{1}{2}m_A v_A^2 = \frac{1}{2}m_B v_B^2\\m_A v_A = 3 m_B v_B$

If we divide first equation by second one we get

$v_A = 3 v_B$

And if we substitute it into the first equation we get

$m_A (3 v_B)^2 = m_B v_B^2\\9 m_A v_B^2 = m_B v_B^2\\m_B = 9 m_A$

So, B has 9 times more mass than A, and so B has 9 times more inertia than A, and their ratio is:

$\frac{I_B}{I_A}=\frac{km_B}{km_A}=\frac{9m_A}{m_A}=9$

7 0

3 years ago

A source produces 20 crests and 20 troughs in 4 seconds. The second crest is 3 cm away from the first crest.Calculate :

sineoko [7]

Answer:

Solution given:

No of waves[N] =20crests & 20 troughs

=20waves

Time[T]=4seconds

distance[d]=3cm=0.03m

Now

Wave length=3cm=3 × ${10}^{ - 2}m$

Frequency= $\frac{No of waves}{time}$

= $\frac{20}{4}$ =5Hertz

and

Wave speed:wave length×frequency=3 × ${10}^{ - 2}m$ ×5=1.5 × ${10}^{ - 1} \tt{ {ms}^{ - 1}}$ .

3 0

3 years ago

The key to most of the achievements of mankind.?

Lapatulllka [165]

Answer:

Greatest Achievements of Mankind

-Declaration of Human Rights.

-United Nations.

-Leonardo Da Vinci's Mona Lisa.

-Michelangelo's Pieta.

-The Works of William Shakespeare.

-Technological achievements.

-The First Flight.

(please mark brainliest if correct/helped you <3)

8 0

3 years ago

If a wave is traveling at a certain speed and it's frequency is doubled,what happens to the wavelength of that water

Elena L [17]

Answer:

If the frequency is doubled the wavelength is only half as long.If you put your fingertip in a pool of water and repeatedly move it up and down,you will create circular water waves.

Hope this helps!!!

4 0

2 years ago

A steam power plant with a power output of 200 MW consumes coal at a rate of 700 tons/h. If the heating value of the coal is 40,

RUDIKE [14]

Answer:

η = 2.57%

Explanation:

Given:

Output power of the steam power plant, P(out) = 200 MW

Consumption of coal, m = 700 tons/h = (700 × 10³)/3600 kg/s= 194.44 kg/s

Heating capacity of the coal, Cv = 40000 kJ/kg

now,

Input power, P(in) = mCv

P(in) = 194.44 kg/s × 40000 = 7777.77 MW

thus,

efficiency, η = P(out)/P(in) = (200 MW) / (7777.77 MW) = 0.02571

η = 2.57%

3 0

3 years ago