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2 years ago

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A coin purse contains d dimes and q quarter's. There are 20 coins in the purse and the total value of the coins is $4.25. Which

coin system of equations represent this situation? A. d+q=4.25, 0.1d+0.25q=20. B.d+q=20, 0.1d+0.25q=4.25. c. d+q=20, d+q=4.25

1 answer:

ch4aika [34]2 years ago

4 0

Answer:

a

Explanation:

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A wire is made from a material having a temperature coefficient of resistivity of 0.0003125 (°C^-1). In an experiment, we mainta

beks73 [17]

Answer:

The power decreases by 36%

Explanation:

Given:

At 20° C

Power, P₀ = 300 W

Potential difference, V = 150 volts

Now, power is given as

P = V²/R

where, R is the resistance

on substituting the values, we get

300 = 150²/R₀

or

R₀ = 75 Ω

Now, the variation of resistance with temperature is given as

R = R₀[1 + α(T - T₀)]

where, α is the temperature coefficient of resistivity = 0.0003125 (°C⁻¹)

now, at

T₀ = 20° C

R₀ = 75 Ω

for

T = 1820° C

we have

R = R₀[1 + α(T - T₀)]

substituting the values

we get

R = 75×[1 + 0.0003125 × (1820 - 20)]

or

R = 117.18 Ω

Now using the formula for power

We have,

P = V²/R

or

P = 150²/117.18 = 192 W

Therefore, the percentage change will be

= $\frac{P-P_0}{P_0}\times 100$

on substituting the values , we get

= $\frac{192-300}{300}\times 100$

= -36%

here, negative sign depicts the decrease in power

3 0

2 years ago

Read 2 more answers

An amusement park ride called the Rotor debuted in 1955 in Germany. Passengers stand in the cylindrical drum of the Rotor as it

steposvetlana [31]

Answer:

μs = 0.36

Explanation:

While the drum is rotating, the riders, in order to keep in a circular movement, are accelerated towards the center of the drum.
This acceleration is produced by the centripetal force.
Now, this force is not a different type of force, is the net force acting on the riders in this direction.
Since the riders have their backs against the wall, and the normal force between the riders and the wall is perpendicular to the wall and aiming out of it, it is easily seen that this normal force is the same centripetal force.
In the vertical direction, we have two forces acting on the riders: the force of gravity (which we call weight) downward, and the friction force, that will oppose to the relative movement between the riders and the wall, going upward.
When this force be equal to the weight, it will have the maximum possible value, which can be written as follows:

$F_{frmax} = \mu_{s}* F_{n} = m * g (1)$

where μs= coefficient of static friction (our unknown)

As we have already said Fn = Fc.
The value of the centripetal force, is related with the angular velocity ω and the radius of the drum r, as follows:

$F_{n} = m* \omega^{2} * r (2)$

Replacing (2) in (1), simplifying and rearranging terms, we can solve for μs, as follows:

$\mu_{s} = \frac{g}{\omega^{2} r} (3)$

Prior to replace ω for its value, is convenient to convert it from rev/min to rad/sec, as follows:

$\omega = 26.0 \frac{rev}{min} * \frac{1min}{60 sec} *\frac{2*\pi rad }{1 rev} = 2.72 rad/sec (4)$

Replacing g, ω and r in (3):
$\mu_{s} = \frac{g}{\omega^{2} r} = \frac{9.8m/s2}{(2.72rad/sec)^{2} *3.7 m} = 0.36 (5)$

3 0

2 years ago

Type the correct answer in the box. use numerals instead of words. anne has a sample of a substance. its volume is 20 cm3, and i

CaHeK987 [17]

The density of sample is 5 g/cm3

Given:

volume of sample = 20 cm3

mass of sample = 100 grams

To Find:

density of sample

Solution: Density is the measure of how much “stuff” is in a given amount of space. For example, a block of the heavier element lead (Pb) will be denser than the softer, lighter element gold (Au). A block of Styrofoam is less dense than a brick. It is defined as mass per unit volume

density = mass/volume

d = 100/20

d = 5 g/cm3

So, density of sample is 5 g/cm3

Learn more about Density here:

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1 year ago

What’s the acceleration if the average velocity is 3.5 and the time is 8.7

Monica [59]

Vf = 0 + 3.5•8.7
= 30.45 m/s

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3 years ago

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Two fat black arrows are swimming along together, when they see a single skinny black arrow coming toward them. They are afraid of strangers, and they know that the skinny one must be mean and tough if it's not afraid to travel alone. So they turn to the side and get out of the skinny arrow's way.

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