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3 years ago

A long-distance runner is running at a constant speed of 5 m/s.

Physics

1 answer:

vivado [14]3 years ago

3 0

Answer:

3.33 minutes (3 minutes and 20 seconds)

Explanation:

Speed of the runner = s = 5 m/s

We need to calculate how will it take for runner to complete 1 km. We have the speed, the distance and we need to find the time. Before performing any calculations, we must convert the values to same units.

Speed is in m/s and distance is in kilometers. So we have to either convert speed to km/s or distance into meters. In this case, converting distance into meters would be a convenient option.

1 kilo meters = 1000 meters

The distance, speed and time are related by the equation:

Distance = Speed x Time

So,

Time = Distance/Speed

Using the values, we get:

t = 1000/5

t = 200 seconds

This means, the runner can complete 1 kilometers in 200 seconds. Since, there are 60 seconds in a minute, we can convert this time to minutes, by dividing it by 60. i.e.

$200 \text{ sec} = \frac{200}{60} \text{ min} = 3.33 \text{ min}$

Thus, it will take the runner 3.33 minutes (3 minutes and 20 seconds) to travel 1 km.

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A basket has a mass of 5.5 kg. Find the magnitude of the normal force if the basket is at rest on a ramp inclined above the hori

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Here is the correct answer of the given problem above.
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1. A listener stands 20.0 m from a speaker that pumps out music with a power output of 100.0 W.

marta [7]

(1.a) The surface area being vibrated by the time the sound reaches the listener is 5,026.55 m².

(1.b) The intensity of the sound wave as it reaches the person listening is 0.02 W/m².

(1.c) The relative intensity of the sound as heard by the listener is 103 dB.

(2.a) The speed of sound if the air temperature is 15⁰C is 340.3 m/s.

(2.b) The frequency of the sound heard by the suspect is 614.3 Hz.

<h3>Surface area being vibrated</h3>

The surface area being vibrated by the time the sound reaches the listener is calculated as follows;

A = 4πr²

A = 4π x (20)²

A = 5,026.55 m²

<h3>Intensity of the sound</h3>

The intensity of the sound is calculated as follows;

I = P/A

I = (100) / (5,026.55)

I = 0.02 W/m²

<h3>Relative intensity of the sound</h3>

$B = 10log(\frac{I}{I_0} )\\\\B = 10 \times log(\frac{0.02}{10^{-12}} )\\\\B = 103 \ dB$

<h3>Speed of sound at the given temperature</h3>

$v= 331.3\sqrt{1 + \frac{T}{273} } \\\\v = 331.3\sqrt{1 + \frac{15}{273} } \\\\v = 340.3 \ m/s$

<h3>Frequency of the sound</h3>

The frequency of the sound heard is determined by applying Doppler effect.

$f_o = f_s(\frac{v \pm v_0}{v \pm v_s} )$

where;

-v₀ is velocity of the observer moving away from the source
-vs is the velocity of the source moving towards the observer
fs is the source frequency
fo is the observed frequency
v is speed of sound

$f_0 = f_s(\frac{v-v_0}{v- v_s} )$

$f_0 = 512(\frac{340.3 - 10}{340.3 - 65} )\\\\f_0 = 614.3 \ Hz$

Learn more about intensity of sound here: brainly.com/question/17062836

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