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2 years ago

An emergency vehicle blowing its siren is moving

Physics

1 answer:

Georgia [21]2 years ago

5 0

The frequency produced by the siren is 631.12 Hz

<h3>Doppler effect</h3>

The variation in frequency when a source of sound moves relative to an observer is determined by the doppler effect.

<h3>Frequency of observer</h3>

So, the frequency of the observer f' = (v ± v')f/(v ± v") where

f' = 590 Hz

f = frequency of source or siren ,

v = speed of sound = 330 m/s,

v' = speed of observer = 0 m/s (since you are stationary) and

v" = speed of source = 23 m/s

Since the source moves away from the detector, the sign in the denominator is positive and v' = 0 m/s

So, f' = (v + 0)f/(v + v")

f' = vf/(v + v")

Since, we require the frequency of the source, make f subject of the formula, we have

<h3>Frequency of siren</h3>

f = (v + v")f'/v

Substituting the values of the variables into the equation, we have

f = (v + v")f'/v

f' = (330 m/s + 23 m/s) × 590 Hz/330 m/s

f' = 353 m/s × 590 Hz/330 m/s

f' = 208270 m/sHz/330 m/s

f' = 631.12 Hz

The frequency produced by the siren is 631.12 Hz

Learn more about doppler effect here:

brainly.com/question/2169203

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Does a compressed spring transfer elastic energy to its surroundings?

shusha [124]

Answer:

Yes

Explanation:

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3 years ago

(15pts) A hungry 12.0 kg fish is coasting from west to east at 75 cm/s when it suddenly swallows a 1 kg fish swimming towards it

faust18 [17]

Answer:

The speed of the big fish after swallowing the small fish is 0.38 m/s.

Explanation:

Consider west to east direction as positive and the opposite direction as negative.

Given:

Mass of big fish (m₁) = 12.0 kg

Initial velocity of big fish (u₁) = 75 cm/s = 0.75 m/s

Mass of small fish (m₂) = 1 kg

Initial velocity of small fish (u₂) = -4 m/s (Direction is opposite to u₁)

After swallowing the small fish, both the fishes move together with same velocity. Let the velocity be 'v'.

So, as there are no effects of drag or any other forces, the given scenario can be considered as a case of inelastic collision where the objects move together with same velocity after collision.

The momentum is conserved in inelastic collision. Therefore,

Initial momentum of the fishes = Final momentum of the fishes

$m_1u_1+m_2u_2=(m_1+m_2)v\\\\v=\dfrac{m_1u_1+m_2u_2}{m_1+m_2}$

Now, plug in the given values and solve for 'v'. This gives,

$v=\frac{12.0\times 0.75+1\times (-4)}{12.0+1}\\\\v=\frac{9-4}{13}\\\\v=\frac{5}{13}=0.38\ m/s$

Therefore, the speed of the big fish after swallowing the small fish is 0.38 m/s

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3 years ago

A ball is thrown horizontally from the top of a building 0.10 km high. The ball strikes the ground at a point 65 m horizontally

aivan3 [116]

Answer:

option B

Explanation:

given,

height of building = 0.1 km

ball strikes horizontally to ground at = 65 m

speed at which the ball strike = ?

vertical velocity = 0 m/s

time at which the ball strike

$s = \dfrac{1}{2}gt^2$

$t = \sqrt{\dfrac{2s}{g}}$

$t = \sqrt{\dfrac{2\times 100}{9.8}}$

t = 4.53 s

vertical velocity at the time 4.53 s = g × t = 9.8 × 4.53 = 44.39 m/s

horizontal velocity = $\dfrac{65}{4.53}$ =14.35 m/s

speed of the ball = $\sqrt{44.39^2+14.35^2}$

= 46.65 m/s

hence, the speed of the ball just before it strike the ground = 47 m/s

The correct answer is option B

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3 years ago

What is the SPEED of a ball that travels 120 m in 6s?

AVprozaik [17]

Answer:

20m/second

Explanation:

The reason the answer is 20m/second is because to find the speed of the ball in this question you have to divide the distance over the time giving you the result of 20m/second

7 0

3 years ago

The gage pressure in a liquid at a depth of 3 m is read to be 39 kPa. Determine the gage pressure in the same liquid at a depth

ioda

Answer: 117 kPa

Explanation:

For the liquid at depth 3 m, the gauge pressure is equal to = P₁=39 kPa

For the liquid at depth 9m, the gauge pressure is equal to= P₂

Now we are given the condition that the liquid is same. That must imply that the density must be same throughout the depth.

So, For finding gauge pressure we have formula P= ρ * g * h

Also gravity also remains same for both liquids

So taking ratio of their respective pressures we have