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Rus_ich [418]
3 years ago
7

A boat travels west at 20km/h. The journey lasts 3hours. How far has the boat travelled?

Physics
2 answers:
zhannawk [14.2K]3 years ago
5 0

Answer:

A boat travels for three hours with a... A boat travels for three hours with a current of 3 mph and then returns the same distance against the current in four hours. What is the boat's speed in still water?

Explanation:

Ganezh [65]3 years ago
4 0

Answer:

20 km/hr x 3hr = 60 km

Explanation:

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Hanna tosses a ball straight up with enough speed to remain in the air for several seconds?
olga_2 [115]
A) the velocity is 0 m/s
3 0
3 years ago
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A visible light has a wavelength of 727.3 nm. Determine its frequency, energy per photon, and color.
Snezhnost [94]

Answer:

f=4.12\times 10^{14}\ Hz and E=2.73\times 10^{-19}\ J

Explanation:

The wavelength of a visible light is 727.3 nm.

727.3\ nm=727.3 \times 10^{-9}\ m

The formula is as follows :

c=f\lambda

f is the frequency of the visible light

f=\dfrac{c}{\lambda}\\\\f=\dfrac{3\times 10^8}{727.3 \times 10^{-9}}\\\\f=4.12\times 10^{14}\ Hz

Energy of a photon is given by :

E = hf, h is Planck's constant

E=6.63\times 10^{-34}\times 4.12\times 10^{14}\\\\E=2.73\times 10^{-19}\ J

Red color has a frequency of 4.12\times 10^{14}\ Hz and energy per photon is 2.73\times 10^{-19}\ J.

3 0
3 years ago
They realize there is a thin film of oil on the surface of the puddle. If the index of refraction of the oil is 1.81, and they o
Sphinxa [80]

Answer:

The right solution is "165.8 nm".

Explanation:

Given:

Index of refraction,

n = 1.81

Wavelength,

λ = 600 nm

We know that,

⇒ t=\frac{\lambda}{2\times n}

By putting the values, we get

      =\frac{600}{2\times 1.81}

      =165.8 \ nm

3 0
3 years ago
In a wire with a 1.05 mm2 cross-sectional area, 7.93×1020 electrons flow past any point during 3.97 s. What is the current ????
34kurt

Answer:

The current in the wire is 31.96 A.

Explanation:

The current in the wire can be calculated as follows:

I = \frac{q}{t}

<u>Where</u>:

q: is the electric charge transferred through the surface

t: is the time      

The charge, q, is:

q = n*e

<u>Where</u>:

n: is the number of electrons = 7.93x10²⁰

e: is the electron's charge = 1.6x10⁻¹⁹ C

q = n*e = 7.93 \cdot 10^{20}*1.6 \cdot 10^{-19} C = 126.88 C

Hence, the current in the wire is:

I = \frac{126.88 C}{3.97 s} = 31.96 A

Therefore, the current in the wire is 31.96 A.

I hope it helps you!

3 0
3 years ago
A woman drops a vibrating tuning fork, which is vibrating at 513 Hertz, from a tall building. Through what distance (in m) has t
umka21 [38]

Answer:

h = 15.34 m

Explanation:

given,

tuning fork vibration = 513 Hz

speed of sound = 343 m/s

frequency after deflection = 489 Hz

the source (the fork) moves away from the observer, its speed increases and hence the apparent frequency decreases

f_{apparent} = \dfrac{v}{v+u}f_0

489 = \dfrac{343}{343+u}\times 513

0.953 = \dfrac{343}{343+u}

343+u = \dfrac{343}{0.953}

343+u = 359.92

u = 16.92 m/s

height of the building

v² = u² + 2 g s

16.92² = 2 x 9.8 x h

h = 14.61 m

time taken by sound to reach observer

t = \dfrac{14.61}{343}

t =0.0426\ s

in this time tuning fork has fallen one more now,

h' = u t + \dfrac{1}{2}gt^2

h' = 16.92\times 0.0426 + \dfrac{1}{2}\times 9.8 \times 0.0426^2

h' = 0.7296 m = 0.73 m

total distance

      h = 14.61 + 0.73

      h = 15.34 m

6 0
3 years ago
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