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3 years ago

What is energy?

Physics

1 answer:

Korvikt [17]3 years ago

4 0

Answer:

Explanation:

c. the ability to do work or to produce heat

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What is the frequency of an electromagnetic wave that has a wavelength of 300,000 km? (the speed of light is 300,000 km/s.)?

expeople1 [14]

Frequency represents the number of complete oscillations in one second. it is measured in Hertz (Hz). Electromagnetic waves are waves which do not require a material media for transmission. They travel with a speed of light.
The speed (m/s) of a wave is given by frequency (Hz) × Wavelength (m)
Speed is 300,000 km/sec or 300,000,000 m/s and the wavelength is 300,000 km or 300,000,000 m.
Frequency = speed÷ wavelength
= 300000000 ÷ 300000000 = 1
Therefore, the frequency of the wave is 1Hz

6 0

3 years ago

An airplane starts from A and flies to B at a constant speed. After reaching B it returns to A at the same speed. There was no w

Dafna1 [17]

Answer:

When there is wind it takes longer

Explanation:

With no wind, the round trip time is

$t_1=\frac{d}{v}+\frac{d}{v}=\frac{2d}{v}$

When we have a constant wind speed w

$t_2=\frac{d}{v-w} +\frac{d}{v+w} =\frac{2vd}{v^{2} -w^{2}}$

comparing the reciprocal times;

$\frac{1}{t_2}=\frac{v^{2}-w^{2} }{2vd}=\frac{v}{2d}-\frac{w^{2}}{2vd} \leq \frac{v}{2d}=\frac{1}{t_1}$

This means that t1 is smaller than t2, ergo, it takes longer with wind

4 0

2 years ago

elements are organized based on their properties on a chart called modern periodic table which of the following statements is tr

Illusion [34]

Answer:

Elements are arranged in the table by increasing atomic number.

Explanation:

In the modern periodic table, each element is represented by its chemical symbol. The number above each symbol is its atomic number.

8 0

3 years ago

What is the pressure exerted by an elephant who weighs 2500N and whose feet cover an area of 7.5m2?

qaws [65]

Answer:

0.00339905404

Explanation:

kg: 0.00339905404

pascals: 333.333333

pounds: 0.0483459126

8 0

3 years ago

If a light is moved twice (2x) as far from a surface, the area the light covers is ___ as big.

Serga [27]

Answer:

The correct option is;

- 4x

Explanation:

From the inverse square law, as the distance from the source of a physical quantity increases, the intensity of the source is spread over an area proportional to the square of the distance of the object from the source

The inverse square law can be presented as follows;

$I = \dfrac{S}{4\times \pi \times r^2 }$

As the distance, r, increases, the surface it covers also increases by the power of 2

Therefore, where the distance increases from r to 2·r, we have;

When, I, remain constant

$I = \dfrac{4\times S}{4\times \pi \times (2\cdot r)^2 } = I = \dfrac{4\times S}{4\times 4\times \pi \times r^2 } = \dfrac{S}{4\times \pi \times r^2 }$

The surface increases to 4·S by the inverse square law

Therefore, the correct option is 4 × x.

3 0

3 years ago