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BigorU [14]
3 years ago
14

5. A man in a car is listening to the radio. The radio station is broadcasting at a frequency of 85 MHz from two radio transmitt

ers immediately behind and immediately in front of the car. At 11.30 am he has excellent reception, but 15 minutes later is has terrible reception. How fast is the car going
Physics
1 answer:
nasty-shy [4]3 years ago
3 0

Answer:

Speed = 0.00392 m/s

Explanation:

Solution:

Frequency of the radio = 85 MHz

If we have the frequency, we can calculate the wavelength of the radio wave.

As we know,

Frequency = speed of light/wavelength

wavelength = c/f

c = speed of light = 3 x 10^{8} m/s

So,

Wavelength =  3 x 10^{8} m/s / 85 x 10^{6} Hz

Wavelength = 3.5294 m

Man gets disturbed reception at t = 15 min

t = 15 x 60 = 900 s

t = 900 s

Speed = distance/time

Here, distance is wavelength. So,

Speed =  3.5294 m / 900 s

Speed = 0.00392 m/s

Hence, the man's car is going with speed of 0.00392 m/s

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Explain why the sound produced by every vibrating body cannot be heard by us ?​
VMariaS [17]

Answer:

The human ear is not sensitive to every frequency of sound, rather, our hearing range is from 20Hz to 20,000Hz. This means sound frequencies outside this range are not audible to the human ear, which is why not every sound produced is heard. This is quite a blessing because if we could hear every vibrating body, then our ears would never stop listening: we won't be able to distinguish 'important sounds' from unimportant ones, rendering our ears effectively useless. Perhaps this is why we have a hearing range in the first place: sounds of our friends and our foes lie in 20Hz-20kHz range.

5 0
3 years ago
Compared to a 1-kg block of solid iron, a 2-kg block of solid iron has twice as much
Tcecarenko [31]

Answer:

D. All of the above.

Explanation:

Iron has a constant density, which means 2-kg block will have twice as much volume as 1-kg block; therefore, choice A is correct.

Inertia is defined by the equation F = ma: it measures how hard it is to change the motion of an object. The inertia of the the 1-kg solid iron is

F = 1a,

And the inertia of the 2-kg solid iron is

F = 2a,

which is twice as much that of the 1-kg block; therefore, choice B is correct.

The mass of the 2-kg block is twice as much as that of the 1-kg block; therefore, choice C is also correct.

Thus, all of the choices are correct (D).

3 0
4 years ago
Which nutrient is the most difficult to break down and, thus, is generally used last for energy in the body?
photoshop1234 [79]

Answer:

proteins

Explanation:

protiens is the most difficult nutrient to brek down

8 0
3 years ago
Read 2 more answers
You push your couch a distance of 3.9 m across the living room floor with a horizontal force of 220.0 n. the force of friction i
Mrac [35]

The general formula to calculate the work is:

W=Fd \cos \theta

where F is the force, d is the displacement of the couch, and \theta is the angle between the direction of the force and the displacement. Let's apply this formula to the different parts of the problem.


(a) Work done by you: in this case, the force applied is parallel to the displacement of the couch, so \theta=0^{\circ} and \cos \theta=1, therefore the work is just equal to the product between the horizontal force you apply to push the couch and the distance the couch has been moved:

W=Fd=(220.0 N)(3.9 m)=858 J


(b) work done by the frictional force: the frictional force has opposite direction to the displacement, therefore \theta=180^{\circ} and \cos \theta=-1. Therefore, we must include a negative sign when we calculate the work done by the frictional force:

W=-Fd=-(144.0 N)(3.9 m)=-561.6 J


(c) The work done by gravity is zero. In fact, gravity (which points downwards) is perpendicular to the displacement of the couch (which is horizontal), therefore \theta=90^{\circ} and \cos \theta=0: this means

W=0.


(d) Work done by the net force:

The net force is the difference between the horizontal force applied by you and the frictional force:

F=220 N-144 N=76 N

And the net force is in the same direction of the displacement, so \theta=0^{\circ} and \cos \theta=1 and the work done is

W=Fd=(76 N)(3.9 m)=296.4 J


4 0
3 years ago
Mention & reasons why the ability to adapt to change is
s2008m [1.1K]

Answer:

The ability to adapt is important because :

1) It helps in the survival of human beings.

2) It brings more variation to the human kind.

3) It helps the species from getting endangered or extinct.

4) It brings transformation in the adapting kind.

Hope this helps you☺️☺️

5 0
3 years ago
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