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3 months ago

A steady circular __________ light means drivers must stop at a marked stop line.

Physics

2 answers:

Maru [3.3K]3 months ago

6 0

Answer:

b. RED

Explanation:

Traffic signals are crucial for directing vehicle movement systematically.

Each signal color conveys a specific directive that drivers must recognize to ensure orderly traffic flow.

For example:

RED: Indicates a stop requirement at the signal

YELLOW: Advises to slow down or prepare to proceed

GREEN: Signals that it is safe to move the vehicle

So, based on this traffic rule, a RED signal necessitates that drivers halt at the designated stop line.

kicyunya [3.2K]3 months ago

5 0

B. red................

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A policeman in a stationary car measures the speed of approaching cars by means of an ultrasonic device that emits a sound with

Ostrovityanka [3204]

Answer:

The beats frequency measures approximately

4.4 kHz

Explanation:

The beat frequency arises from the original ultrasound frequency, $f=41.2 kHz$ , and the frequency of the sound reflected off the car, $f'$ :

$f_B = f'-f$ (1)

To calculate the frequency of the reflected sound, we apply the Doppler effect formula:

$f'=\frac{v}{v-v_s}f$

where

v = 340 m/s, the speed of sound

$v_s =33.0 m/s$ is the velocity of the car

$f=41.2 kHz$ is the frequency of the sound emitted

By substituting values,

$f'=\frac{340 m/s}{340 m/s-33.0 m/s}(41.2 kHz)=45.6 kHz$

Thus, the beat frequency (1) is

$f_B = 45.6 kHz - 41.2 kHz=4.4 kHz$

3 0

3 months ago

Read 2 more answers

A supersonic nozzle is also a convergent–divergent duct, which is fed by a large reservoir at the inlet to the nozzle. In the re

Softa [3030]

Answer:

155.38424 K

2.2721 kg/m³

Explanation:

$P_1$ = Reservoir pressure = 10 atm

$T_1$ = Reservoir temperature = 300 K

$P_2$ = Exit pressure = 1 atm

$T_2$ = Exit temperature

$R_s$ = Specific gas constant = 287 J/kgK

$\gamma$ = Specific heat ratio = 1.4 for air

Assuming isentropic flow

$\frac{T_2}{T_1}=\frac{P_2}{P_1}^{\frac{\gamma-1}{\gamma}}\\\Rightarrow T_2=T_1\times \frac{P_2}{P_1}^{\frac{\gamma-1}{\gamma}}\\\Rightarrow T_2=00\times \left(\frac{1}{10}\right)^{\frac{1.4-1}{1.4}}\\\Rightarrow T_2=155.38424\ K$

Flow temperature at exit is 155.38424 K

Density at exit can be derived using the ideal gas equation

$\rho_2=\frac{P_2}{R_sT_2}\\\Rightarrow \rho=\frac{1\times 101325}{287\times 155.38424}\\\Rightarrow \rho=2.2721\ kg/m^3$

Flow density at exit measures 2.2721 kg/m³

4 0

4 months ago