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Svetllana [295]

3 years ago

14

Which is less likely to be reliable source of information,the webpage of a university or the webpage of a scientist who is tryin

g to sell a new invention explain

2 answers:

Nikolay [14]3 years ago

6 0

The scientist because he is biased and a university isn't. The scientist will say good things about the invention to sell more of it. Hope this helps! ;)

beks73 [17]3 years ago

3 0

A university because its mostly updated most ofteb yanno? but if you dont agree with me its fine

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A crate weighing 1000 Newton's needs to be lifted at a constant speed from the ground to a loading dock 1.5 meters high in 5.0 s

miskamm [114]

Answer:

the Power required is 300 W

Explanation:

We know that the definition of work is given by the following expresion:

$W=F*d$

the distance is 1.5 meters and the Force is equal to 1000 N.

Replacing this values in the work expresion

$w= 1000 *1.5 = 1500 J$

And the power is equal to the amount of work done in a given time, therefore we have:

$Power = \frac{work}{time} \\$

Time in seconds

$Power = 1500/5\\\\Power = 300 watts$

3 0

3 years ago

A fire truck emits an 880Hz siren. As the truck approaches an observer on the sidewalk, he perceives the pitch to be 950Hz. Appr

Ludmilka [50]

Answer:

The pitch that he hears after the truck passes and is moving away is 819.6 Hz.

Explanation:

The pitch that he hears after the truck passes and is moving away can be calculated using the following equation:

$f = f_{0}*\frac{v_{s} \pm v_{o}}{v_{s} \pm v_{f}}$

Where:

$f$ : is the perceived frequency

$f_{0}$ : is the emitted frequency

$v_{s}$ : is the speed of sound = 340 m/s

$v_{o}$ : is the speed of the observer = 0 (he is not moving)

$v_{f}$ : is the speed of the fire truck

First, we need to find the speed of the fire truck. When it approaches the observer we have:

$f = f_{0}*\frac{v_{s} + v_{o}}{v_{s} - v_{f}}$

$950 Hz = 880 Hz*\frac{340 m/s}{340 m/s - v_{f}}$

$v_{f} = 340 m/s - \frac{880 Hz*340 m/s}{950 Hz}$

$v_{f} = 25.05 m/s$

Hence, the speed of the fire truck is 25.05 m/s.

Now, we can calculate the pitch that the observer hears after the truck passes:

$f = f_{0}*\frac{v_{s} - v_{o}}{v_{s} + v_{f}}$

$f = 880 Hz*\frac{340 m/s}{340 m/s + 25.05 m/s}$

$f = 819.6 Hz$

Therefore, the pitch that he hears after the truck passes and is moving away is 819.6 Hz.

I hope it helps you!

7 0

3 years ago

A material having an index of refraction of 1.35 is used as an antireflective coating on a piece of glass (n = 1.50). What shoul

exis [7]

Answer:

103.70 nm

Explanation:

The minimum thickness of the film is given by $t=\frac{\lambda }{4n}$ where $\lambda$ is the wavelength and n is the index of the refraction

We have n =1.35

Wavelength $\lambda =560nm$

So the minimum thickness of the film $t=\frac{\lambda }{4n}=\frac{560}{4\times 1.35}=103.70\ nm$

3 0

3 years ago

The slight negative charge at one end of one water molecule is attracted to the slight positive charge of another water molecule

aleksley [76]

Electromagnetic force. It is where alike forces ( negative, negative & positive , positive) repel and opposite forces ( negative & positive ) attract.
Hopes this helped

7 0

4 years ago

Three materials, put them in order of what

Grace [21]

Answer:

it's a

Explanation:

hope this helps!!!!!!

4 0

3 years ago