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prohojiy [21]
4 years ago
15

An Olympic runner competing in a long-distance event finishes with a time of 2 hours, 45 minutes, and 35 seconds. The event has

a distance of 27.3 miles. What is the average speed of the runner in kilometers per hour?
Physics
1 answer:
Readme [11.4K]4 years ago
6 0

Answer:

Average speed of Olympic runner will be 23.08 km/hr

Explanation:

We have given distance d = 27.3 miles

We know that 1 mile = 1.6 km

So 27.3 mile = =27.3\times 1.6=43.68km

Given time = 2 hour 45 minutes and 35 sec

We know that 1 hour = 60 minutes

So 45 minutes =\frac{45}{60}=0.75hour

We also know that 1 hour = 3600 sec

So 1 sec =\frac{1}{3600}=2.777\times 10^{-4}hour

So total time t ==2+0.75+0.000277=2.750277hour

We know that speed =\frac{distance}{time }=\frac{63.48}{2.750277}=23.08km/hour

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Sam is conducting an experiment in a closed room. He places two sound-generating instruments, A and B, in different places in th
diamong [38]

Answer: The correct answer is "Instrument A is placed closer to Sam than instrument B".

Explanation:

The sound can be soft or loud. Loudness depends on the amplitude of the sound wave. Higher the amplitude, more will be loudness. Lower the amplitude, lesser will be loudness.

Pitch depends on the frequency.

In the given problem, the instruments A and B generate sound waves of the same amplitude and at the same time.

Loudness depends on the sound energy produced as the energy of the sound is directly proportional to the square of the amplitude. It also depends on the distance between the source and the receiver.

Sam records a louder sound from instrument A than from instrument B. It means that there is mismatch in loudness. It can happen due to the placement of the instrument A closer to Sam than instrument B.

Therefore, the correct option is "Instrument A is placed closer to Sam than instrument B".

4 0
4 years ago
The speed of light in a transparent medium is 0.6 times that of its speed in vacuum. Find the refractive index of the medium.
grin007 [14]
<h2>Answer:</h2>

The refractive index is 1.66

<h2>Explanation:</h2>

The speed of light in a transparent medium is 0.6 times that of its speed in vacuum .

Refractive index of medium = speed of light in vacuum / speed of light in medium  

So

RI = 1/0.6 = 5/3 or 1.66

3 0
3 years ago
Read 2 more answers
How does charging by conduction work?
anzhelika [568]

Answer:

During charging by conduction, both objects acquire the same type of charge. If a negative object is used to charge a neutral object, then both objects become charged negatively. ... In this case, electrons are transferred from the neutral object to the positively charged rod and the sphere becomes charged positively.

6 0
4 years ago
I need to solve this problem ​
castortr0y [4]

Answer:

λ = V / f      the wavelength versus the frequency

V = f λ      and V (speed) proportional λ    for a fixed frequency

F = f^2 * (M / L) * λ^2 = (f * λ)^2 * (M / L)^2    force (tension) on string at a given frequency

F2 / F1 = (λ2 / λ1)^2    other items are constant

Let λ1  = 6   then λ2 must be 3/2 λ1   for a constant length

F2 / F1 = (6 / 4)^2 = 9/4

The tension must be increased to 9 / 4 of  the original tension

Check: if the frequency is fixed then V will be larger for a larger wavelength  (situation 2)

One can also write V = (F / (M / L))^1/2

Then for fixed M  L    

F2 / F1 = (V2 / V1)^2

Since V = f λ      Velocity is proportional to λ  for a fixed frequency

Then if V2 / V1 = 3 / 2     F2 = 9/4 F1

 

4 0
2 years ago
A balky cow is leaving the barn as you try harder and harder to push her back in. In coordinates with the origin at the barn doo
Tresset [83]

Answer:

The work done is -209.42 J.

Explanation:

F(x) = (- 20 - 3 x ) N

x = 0 to x = 6.9 m

Here, the force is variable in nature, so the work done by the variable force is given by

W =\int F dx\\\\W =\int_{0}^{6.9}(-20- 3x dx )\\\\W= \left [ - 20 x - 1.5 x^2 \right ]_{0}^{6.9}\\\\W = - 20 (6.9 - 0) - 1.5(6.9\times 6.9 - 0)\\\\W =- 138 - 71.42\\\\W = - 209.42  J

7 0
3 years ago
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