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cluponka [151]
3 years ago
5

At rest, a car’s horn sounds the note A (440 Hz). The horn is sounded while the car is moving down the street. A bicyclist movin

g in the same direction with one-third the car’s speed hears a frequency of 415 Hz. (a) Is the cyclist ahead of or behind the car? (b) What is the speed of the car?
Physics
1 answer:
coldgirl [10]3 years ago
4 0

Answer:

(a): The cyclist is behind the car.

(b): The speed of the car are Vf= 31.97 m/s.

Explanation:

f= 440 Hz

f'= 415 Hz

Vo= 1/3 Vf

Vf= ?

V= 343.2 m/s

f'= f* ( (V-(-Vo) / (V-(-Vf) )

clearing Vf :

Vf= 31.97 m/s

Vo= 10.65 m/s

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A well-trained athlete can run 400m in 47s, what is the athlete’s velocity?
AnnZ [28]

Answer:

8.51 m/s

Explanation:

Velocity = Displacement/Time

Velocity = 400 m ÷ 47 s

<u>Velocity</u><u> </u><u>=</u><u> </u><u>8</u><u>.</u><u>5</u><u>1</u><u> </u><u>m</u><u>/</u><u>s</u>

7 0
2 years ago
6. A lumberjack is standing on a log floating on a lake. She starts from rest, then runs along the log to the end, when she jump
scoray [572]

Answer:

a) -3.267 m/s

b) 2.227 m/s

Explanation:

As per the conservation of momentum

m1v1 + m2v2=0

m1= mass of log

m2 = mass of lumber jack

v1 = velocity of log

v2 = velocity of lumber jack

a) Velocity of first log

-\frac{70*7}{150} = -3.267 m/s

b) m1v1 + m2v2 = m3v3

Velocity of log

= \frac{70*7}{150+70} \\2.227

4 0
3 years ago
The vitreous humor, a transparent, gelatinous fluid that fills most of the eyeball, has an index of refraction of 1.34. Visible
Leto [7]

Answer:

a)   298.5 nm ,  522.4 nm  and b)  radiation frequency does not change

Explanation:

When electromagnetic radiation reaches a medium with a different index of refraction, the medium vibrates the molecules, as if it were a resonance process, whereby the medium vibrates at the same frequency as the incident light.

On the other hand, when the light reaches another medium its average speed within the medium changes, it is now less than the speed of light in a vacuum (c) for this to happen as we saw that the frequency is constant there must be a change in the wavelength of the radiation that is characterized by the ratio

    λₙ = λ₀ / n

    λₙ = 400 nm    in the void

    λₙ = 400 / 1.34

    λₙ= 298.5 nm

   λ₀ = 700 nm

   λₙ = 700 / 1.34

   λₙ = 522.4 nm

The radiation frequency does not change

4 0
3 years ago
A stone is dropped into a river from a bridge 41.7 m above the water. Another stone is thrown vertically down 1.80 s after the f
hram777 [196]

Answer:

31.75 m/s

Explanation:

h = 41.7 m

Let the initial velocity of the second stone is u

Let the time taken to reach to the bottom by the first stone is t then the time taken by the second stone to reach the ground is t - 1.8.

For first stone:

Use second equation of motion

h=ut+\frac{1}{2}gt^2

Here, u = 0, g = 9.8 m/s^2 and t be the time and h = 41.7

So, 41.7= 0 + 0.5 x 9.8 x t^2

41.7 = 4.9 t^2

t = 2.92 s ..... (1)

For second stone:

Use second equation of motion

h=ut+\frac{1}{2}gt^2

Here, g = 9.8 m/s^2 and time taken is t - 1.8 = 2.92 - 1.8 = 1.12 s, h = 41.7 m and u be the initial velocity

h=u\left ( t-1.8 \right )+4.9\left ( t-1.8 \right )^2    .... (2)

By equation the equation (1) and (2), we get

41.7=1.12 u +4.9 \times 1.12^{2}

u = 31.75 m/s

5 0
3 years ago
You lift a large bag of flour from the floor to a 2.5m high counter, doing 400J of work in 2 seconds. How much force did you app
oksian1 [2.3K]
<h2>The man have to apply force of 160 N</h2>

Explanation:

The work done to lift the bag of weight mg through height 2.5 m is 400 J

The work done can be found by relation  W = mg x h

Thus mg = \frac{W}{h} = \frac{400}{2.5} =  160 N

Therefore the man have to apply the force of 160 N

7 0
3 years ago
Read 2 more answers
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