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3 years ago

What happens to the sound of a train whistle as a train approaches and passes you? why?

1 answer:

8 0

This is called, The Doppler effect.

In short terms, when the trains is farther away the wavelength of the whistles sound are longer and more separate from each other, and more farther away from you, as it gets closer to you, the wavelengths start getting shorter and more louder the closer it gets to you. Basically the <span>wavelengths change because of the motion of the source.</span>

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he measured flow rate of water through a 20 mm diameter pipe is 75 L/min. What is the average velocity (in m/s) of water flowing

Masteriza [31]

Answer:

Average velocity of water flow through the pipe = 3.98 m/s

Explanation:

Diameter of pipe = 20 mm

Discharge = 75 L/min

We know that

Discharge = Area x Velocity

$\texttt{Area of pipe}=\frac{\pi d^2}{4}=\frac{\pi \times (20\times 10^{-3})^2}{4}=3.14\times 10^{-4}m^2$

Discharge = 75 L/min

$=\frac{75\times 10^{-3}}{60}=1.25\times 10^{-3}m^3/s$

Substituting

$1.25\times 10^{-3}=3.14\times 10^{-4}\times V\\\\V=3.98m/s$

Average velocity of water flow through the pipe = 3.98 m/s

6 0

3 years ago

Does a can opener make work easier by increasing force, increasing distance, or changing direction?

ivann1987 [24]

A can opener makes work easier by increasing force.

Explanation

Technically a can opener is a simple lever that increases the force with which we remove the cap of the can. Levers are rod shaped objects with fulcrum at one end and the length of the lever has a positive impact on the force.

considering the equation

work=force*distance

indicates that increasing the length of the lever/can opener increases the work done by it.

6 0

3 years ago

A cylindrical tank has a radius of 53 cm and a height of 1200 mm. It weighs 9.6 kN

xxTIMURxx [149]

Answer:

1985kg

Explanation:

assuming that

pi =3.14

oil density = 950kg/ cubic meter

g= 9.8m/s

$M=\frac{9600}{9.8 } + 950 * 3.14*.53^{2} *1.2=1985kg$

4 0

3 years ago

Josie sees lightning off in the distance. A few seconds later she hears thunder. What can Josie conclude?

Naddik [55]

Light wave travel faster than sound waves

8 0

3 years ago

Read 2 more answers

How Does Earth's gravitational force field act on objects that aren't touching Earth's surface?

natali 33 [55]

Answer:

Explanation:

Gravity is a field force since the earth does not have to actually “touch” an object to pull it toward the earth. A magnetic force is a field force that attracts or repels another magnet. Likewise, electric charges cause attracting or repelling forces without actual contact between the charges

8 0

2 years ago