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alexandr1967 [171]

4 years ago

7

a sound with a constant frequency is produced by the siren on top of a firehouse. Compared to the frequency produced by the sire

n,the frequency observed by a firefighter approaching the fire house is

1 answer:

polet [3.4K]4 years ago

3 0

There's an effect called The Doppler Effect, that's the "up and down" sound.
That frequency is 1.8mm and 115 per minute.

(Hope this helped.)

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I have a voltage source of 12V but a light that only burns at 5V. The lamp works on 18 mA. Calculate the resistance that you EXT

ratelena [41]

Answer:

The resistance that will provide this potential drop is 388.89 ohms.

Explanation:

Given;

Voltage source, E = 12 V

Voltage rating of the lamp, V = 5 V

Current through the lamp, I = 18 mA

Extra voltage or potential drop, IR = E- V

IR = 12 V - 5 V = 7 V

The resistance that will provide this potential drop (7 V) is calculated as follows:

IR = V

$R = \frac{V}{I} = \frac{7 \ V}{18 \times 10^{-3} A} \ = 388.89 \ ohms$

Therefore, the resistance that will provide this potential drop is 388.89 ohms.

7 0

3 years ago

An eagle carrying a trout flies above a lake along a horizontal path. The eagle drops the trout from a height of 6.1 m. The fish

Snezhnost [94]

Answer:

7.1 m/s

Explanation:

First, find the time it takes for the fish to reach the water.

Given in the y direction:

Δy = 6.1 m

v₀ = 0 m/s

a = 9.8 m/s²

Find: t

Δy = v₀ t + ½ at²

6.1 m = (0 m/s) t + ½ (9.8 m/s²) t²

t = 1.12 s

Next, find the velocity needed to travel 7.9 m in that time.

Given in the x direction:

Δx = 7.9 m

a = 0 m/s²

t = 1.12 s

Find: v₀

Δx = v₀ t + ½ at²

7.9 m = v₀ (1.12 s) + ½ (0 m/s²) (1.12 s)²

v₀ = 7.1 m/s

4 0

4 years ago

Read 2 more answers

A 1500 kg truck is acted upon by a force that decreases its speed from 25 m/s to 15 m/s in 8 s. What is the magnitude of the for

Citrus2011 [14]

Answer:

F = 1,875 N

Explanation:

force=

$\frac{change \: in \: momentum}{time \: taken}$

∆H = m∆V

where ∆H ----> change in momentum.

( final momentum - initial momentum )

and ∆V ----> change in velocity

( final velocity - initial velocity )

and m ----> is mass

then f =

$\frac{1500 \times (25 - 15)}{8}$

= 1,875 N

4 0

3 years ago

Five properties of magnet

Olenka [21]

Answer:

1. The magnet is magnetic and can attract iron articles.

2. The magnet has magnetic poles. Each magnet has two kinds of poles: N pole and S pole. They are in pairs.

3. Temporary magnet and permanent magnet: when the ferromagnetic material is magnetized, it is easy to lose the magnetic property, which is called temporary magnet (for example: iron); when the ferromagnetic material is magnetized, it is not easy to lose the magnetic property, which is called permanent magnet (for example: steel).

4. When two magnets are close to each other, the same poles will repel and push away from each other, and the different poles will attract and stick to each other. Therefore: the same pole repels each other, the different pole attracts each other.

5. The attraction of a magnetic object is called magnetism. An object is surrounded by a magnetic material. The area affected by the magnetic force is called the magnetic field.

3 0

3 years ago

Calculate the wavelength in centimeters of radar energy at a frequency of 10 GHz. What is the frequency in gigahertz of radar en

konstantin123 [22]

Explanation:

(a) Frequency of radar energy, $f = 10\ GHz =10^{10}\ Hz$

The relation between frequency and wavelength is given by :

$c=f\lambda$

$\lambda=\dfrac{c}{f}$

$\lambda=\dfrac{3\times 10^8}{10^{10}}$

$\lambda=0.03\ m$

or

$\lambda=3\ cm$

(b) If wavelength, $\lambda=25\ cm=0.25\ m$

$c=f\lambda$

$f=\dfrac{c}{\lambda}$

$f=\dfrac{3\times 10^8}{0.25}$

$f=1.2\times 10^9\ Hz$

or

f = 1.2 GHz

Hence, this is the required solution.

7 0

3 years ago