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4 years ago

15

What force causes a wagon to speed up as it rolls down a hill?

1 answer:

netineya [11]4 years ago

7 0

The answer would be "gravity" because gravity is pulling the wagon down the hill.

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What part of the electromagnetic spectrum can be seen by humans

Amanda [17]

Answer:

Visible light

Explanation:

Electromagnetic spectrum is the classification of the electromagnetic waves according to their frequency/wavelength. In order from the shortest to the longest wavelength, we have

Gamma rays

X-rays

Ultraviolet

Visible light

Infrared

Microwaves

Radio waves

All these waves are invisible to human eye, except for the part referred as 'visible light'. The electromagnetic waves of this part of the spectrum are visible to human eye, and they appear as a different color depending on their wavelength. In particular, we have:

Violet: 380-450 nm

Blue: 450-495 nm

Green: 495-570 nm

Yellow: 570-590 nm

Orange: 590-620 nm

Red: 620-750 nm

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3 years ago

What is Marie's instantaneous speed at 20 minutes in miles/min?

AVprozaik [17]

Answer:

0.25miles/min

Explanation:

Instantaneous speed of a person or an object is its speed at a particular moment usually at a period of time.

The speedometer of a car reports the instantaneous speed.

It can be mathematically expressed as;

Instantaneous speed = $\frac{distance}{time}$

At 20min the distance covered is 5miles;

Instantaneous speed = $\frac{5 miles }{20mins}$ = 0.25miles/min

8 0

3 years ago

A sinusoidal voltage is given by the expression ????(????)=20cos(5π×103 ????+60°) V. Determine its (a) frequency in hertz, (b) p

MA_775_DIABLO [31]

<em>There are some placeholders in the expression, but they can be safely assumed</em>

Answer:

(a) $f=1617.9\ Hz$

(b) $T=0.618\ ms$

(c) $A=20 \ Volts$

(d) $\varphi=60^o$

Explanation:

<u>Sinusoidal Waves </u>

An oscillating wave can be expressed as a sinusoidal function as follows

$V(t)&=A\cdot \sin(2\pi ft+\varphi )$

Where

$A=Amplitude$

$f=frequency$

$\varphi=Phase\ angle$

The voltage of the question is the sinusoid expression

$V(t)=20cos(5\pi\times 103t+60^o)$

(a) By comparing with the general formula we have

$f=5\pi\times 103=1617.9\ Hz$

$\boxed{f=1617.9\ Hz}$

(b) The period is the reciprocal of the frequency:

$\displaystyle T=\frac{1}{f}$

$\displaystyle T=\frac{1}{1617.9\ Hz}=0.000618\ sec$

Converting to milliseconds

$\boxed{T=0.618\ ms}$

(c) The amplitude is

$\boxed{A=20 \ Volts}$

(d) Phase angle:

$\boxed{\varphi=60^o}$

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3 years ago

Decomposition breaks down organic material into simpler units and:

Lady_Fox [76]

Answer:

d.) provides proteins for plants

Explanation:

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3 years ago

If we assume that, in the African savanna, rainfall and the amount of grass is plentiful, what other factor would BEST explain a

valentina_108 [34]

Diseases, Hunting (sport for humans), predators

8 0

4 years ago

Read 2 more answers