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3 years ago

A train travels 57 kilometers in 3 hours, and then 87 kilometers in 2 hours. What is its average speed? km/hr

1 answer:

3 0

Average speed (v) = total distance(d) / total time (t)
d = 57 + 87km = 144km
t = 2 + 3hrs = 5hrs
v = d÷t = 144÷5 = 28.8km/hr

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Một ô tô bắt đầu chuyển động thẳng nhanh dần đều,sau 10 giây đạt vận tốc 72km/h.Gia tốc của ô tô là

NeTakaya

Answer:

van

Explanation:

7 0

2 years ago

Read 2 more answers

A wave has a wavelength of 4. 9 m and a velocity of 9. 8 m/s. The medium through which this wave is traveling is then heated so

tatiyna

The wavelength of a wave is obtained by taking the ratio of wave speed and frequency.

The wavelength of the heated wave is 9.8 m. Hence, option (b) is correct.

What is frequency of a wave?

The number of oscillations completed by a wave in one second is known as the frequency of a wave. It is expressed as the ratio of the velocity of the wave to its wavelength.

Given data-

The wavelength of the wave is, $\lambda = 4.9 \;\rm m$ .

The velocity of the wave is, v = 9.8 m/s.

The mathematical expression for the frequency of the wave is,

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

Solving as,

$f = \dfrac{9.9}{4.9}\\\\f =2 \;\rm Hz$

Now, with constant frequency and the double magnitude of velocity (v' = 2 × 9.8 = 19.6 m/s). The wavelength of the heated wave is calculated as,

$f = \dfrac{v'}{\lambda'}$

here,

$\lambda'$ is the wavelength of the heated wave.

Solving as,

$2 = \dfrac{19.6}{\lambda'}\\\\\lambda' = \dfrac{19.6}{2}\\\\\lambda' = 9.8 \;\rm m$

Thus, we can conclude that the wavelength of the heated wave is 9.8 m. Hence, option (b) is correct.

Learn more about the frequency of wave here:

brainly.com/question/1324797

3 0

3 years ago

A construction crane, like the one shown, has a power output of 1,500 watts. If it takes 200 seconds to lift the roof to the top

Likurg_2 [28]

Answer:7.5j

Explanation:

P=w/s

4 0

3 years ago

If the Sun suddenly went dark, we would not know it until its light stopped arriving on Earth. How long would that be, in second

Gre4nikov [31]

Answer: 500 s

Explanation:

Speed $v$ is defined as a relation between the distance $d$ and time $t$ :

$v=\frac{d}{t}$

Where:

$v=3(10)^{8}m/s$ is the speed of light in vacuum

$d=1.5(10)^{11}m$ is the distance between the Earth and Sun

$t$ is the time it takes to the light to travel the distance $d$

Isolating $t$ :

$t=\frac{d}{v}$

$t=\frac{1.5(10)^{11}m}{3(10)^{8}m/s}$

Finally:

$t=500 s$

5 0

3 years ago

What is a element that tends to be shiny, easy shaped, and a good conductor of heat?

ozzi

The answer to your question is Metal

8 0

3 years ago