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Lesechka [4]
3 years ago
15

Một ô tô đi với vận tốc 60 km/h trên nửa phần đầu của đoạn đường AB. Trong nửa đoạnđường còn lại ô tô đi nửa thời gian đầu với v

ận tốc 40 km/h và nửa thời gian sau với vận tốc 20 km/h. Tính tốc độ trung bình của ô tô ?
Physics
1 answer:
melamori03 [73]3 years ago
4 0

Answer:

Huhfgyyeyvvucvyehukfsdjbjz/////???

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1 poi
tatuchka [14]

Answer:

true

Explanation:

for example assume you are setting in a moving bus and when someone see you from the ground you are in motion but for some who is with you in the bus you are not in motion.

6 0
3 years ago
In order to effectively radiate a radio signal, an antenna must be at least one-half the wavelength of transmission in length, i
Virty [35]
<span>The equation that relates Wavelength & frequency of electromagnetic waves is : Velocity (c) = Wavelength (λ) * frequency (f) ------ (1) Electromagnetic wave velocity (c) = Speed of Light = 3 * 10^8 m/s From (1), Wavelength , λ = c / f λ= (3*10^8)/(980*10^3) λ = 306.12 m Minimum height of the antenna for effective transmission = λ * 0.5 = 306.12*0.5 Answer : 153 m (rounded off)</span>
6 0
3 years ago
A very long string (linear density 0.7 kg/m ) is stretched with a tension of 70 N . One end of the string oscillates up and down
rewona [7]

To develop this problem it is necessary to apply the concepts related to Wavelength, The relationship between speed, voltage and linear density as well as frequency. By definition the speed as a function of the tension and the linear density is given by

V = \sqrt{\frac{T}{\rho}}

Where,

T = Tension

\rho = Linear density

Our data are given by

Tension , T = 70 N

Linear density , \rho = 0.7 kg/m

Amplitude , A = 7 cm = 0.07 m

Period , t = 0.35 s

Replacing our values,

V = \sqrt{\frac{T}{\rho}}

V = \sqrt{\frac{70}{0.7}

V = 10m/s

Speed can also be expressed as

V = \lambda f

Re-arrange to find \lambda

\lambda = \frac{V}{f}

Where,

f = Frequency,

Which is also described in function of the Period as,

f = \frac{1}{T}

f = \frac{1}{0.35}

f = 2.86 Hz

Therefore replacing to find \lambda

\lambda = \frac{10}{2.86}

\lambda = 3.49m

Therefore the wavelength of the waves created in the string is 3.49m

3 0
4 years ago
A mass weight of 120N is hung from two strings. what is the tension?
kramer
The weight should be shared between the two string equally. Therefore, tension in each string, T is;

T = 120 N/2 = 60 N
7 0
3 years ago
Read 2 more answers
The current in the circuit shown is 2.0 A.
andrezito [222]

The value of R3 is A) 10 Ω

8 0
3 years ago
Read 2 more answers
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