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sergeinik [125]

3 years ago

6

If you see that a hot-air balloon is rising above the top of a hill, what is the top of the hill called? A. delta point B. dista

nce system C. coordinate system D. reference point

2 answers:

klasskru [66]3 years ago

6 0

If you see that a hot-air balloon is rising above the top of a hill, the top of the hill is called the reference point. Correct answer: D The reference point is a point (object, place) used for comparison to determine if something is in motion, assuming that the reference point is stationary, or not moving.

MrRissso [65]3 years ago

5 0

The answer is reference point.

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1d. Conservation of energy is demonstrated in this roller coaster example.

Dvinal [7]

Answer:

can you clear your question I can't understand

6 0

3 years ago

(a) According to Hooke's Law, the force required to hold any spring stretched x meters beyond its natural length is f(x)=kx. Sup

KengaRu [80]

Answer:

a) The work required to stretch the spring from 20 centimeters to 25 centimeters is 0.313 joules, b) The area of the region enclosed by one loop of the curve $r(\theta) = 2\cdot \sin 5\theta$ is $4\pi$ .

Explanation:

a) The work, measured in joules, is a physical variable represented by the following integral:

$W = \int\limits^{x_{f}}_{x_{o}} {F(x)} \, dx$

Where

$x_{o}$ , $x_{f}$ - Initial and final position, respectively, measured in meters.

$F(x)$ - Force as a function of position, measured in newtons.

Given that $F = k\cdot x$ and the fact that $F = 25\,N$ when $x = 0.3\,m - 0.2\,m$ , the spring constant ( $k$ ), measured in newtons per meter, is:

$k = \frac{F}{x}$

$k = \frac{25\,N}{0.3\,m-0.2\,m}$

$k = 250\,\frac{N}{m}$

Now, the work function is obtained:

$W = \left(250\,\frac{N}{m} \right)\int\limits^{0.05\,m}_{0\,m} {x} \, dx$

$W = \frac{1}{2}\cdot \left(250\,\frac{N}{m} \right)\cdot [(0.05\,m)^{2}-(0.00\,m)^{2}]$

$W = 0.313\,J$

The work required to stretch the spring from 20 centimeters to 25 centimeters is 0.313 joules.

b) Let be $r(\theta) = 2\cdot \sin 5\theta$ . The area of the region enclosed by one loop of the curve is given by the following integral:

$A = \int\limits^{2\pi}_0 {[r(\theta)]^{2}} \, d\theta$

$A = 4\int\limits^{2\pi}_{0} {\sin^{2}5\theta} \, d\theta$

By using trigonometrical identities, the integral is further simplified:

$A = 4\int\limits^{2\pi}_{0} {\frac{1-\cos 10\theta}{2} } \, d\theta$

$A = 2 \int\limits^{2\pi}_{0} {(1-\cos 10\theta)} \, d\theta$

$A = 2\int\limits^{2\pi}_{0}\, d\theta - 2\int\limits^{2\pi}_{0} {\cos10\theta} \, d\theta$

$A = 2\cdot (2\pi - 0) - \frac{1}{5}\cdot (\sin 20\pi-\sin 0)$

$A = 4\pi$

The area of the region enclosed by one loop of the curve $r(\theta) = 2\cdot \sin 5\theta$ is $4\pi$ .

5 0

3 years ago

True or false: Everything in the universe works with harmony because of balanced energy

Eduardwww [97]

Answer:

Explanation:

True

7 0

3 years ago

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Which of the following is/are true? Electromagnetic waves are created by accelerating charges. Electromagnetic waves are transve

Vikki [24]

Answer:

All of the above are true.

Explanation:

(a). true

whenever charge particle move back and froth from its mean position then it will produce oscillating electric and magnetic fields, . so an em wave can be obtain by accelerating charge

(b). true

the electric field and the magnetic field have vibrations in the perpendicular direction along the motion of the wave so electromagnetic wave is a transverse wave. therefore, the EM wave is a Transverse wave

(c) true .

The Electromagnetic wave consists of the two mutually perpendicular electric and magnetic fields and also both fields are perpendicular to the direction of propagation of the wave.

(d) true .

An electromagnetic wave carry energy through vacuum with a speed of $3 \times 10^8 m/s$

so , all of the above are true.

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3 years ago

15) Very cold climates occur at Earth's North and South Poles because the polar regions

Gwar [14]

Because the polar regions receive low-angle insolation.

Insolation is the amount of solar radiation received by a given area. The Sun is always low on the horizon. The low Sun angle makes the beam of solar radiation to travel a longer distance from upper troposphere to reach earth's surface as compared to when it is directly overhead. In this case, the radiations are scattered and reflected more by the atmosphere and spread over a larger area. Thus, the intensity of solar radiation is very less at polar regions than near the equatorial region. This is the reason of very cold climates at polar regions.

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3 years ago

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