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2 years ago

A newspaper turns yellow in sunlight. Is this a physical or chemical change?

1 answer:

5 0

It is a chemical change. I always think of a chemical/physical change as if you could reverse it back as it started off, for example if you stepped on a can you can reverse the can back probably not exactly like it was before but you can still reverse it so this would be a physical change, and if you baked a pizza you could not reverse the dough and everything else back.

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A physics professor demonstrates the Doppler effect by tying a 600 Hz sound generator to a 1.0-m-long rope and whirling it aroun

nalin [4]

Answer:

Therefore the the highest frequency is 620Hz and lowest frequency is 580Hz

Explanation:

Given data

Source Frequency fs=600Hz

Length r=1.0m

RPM=100 rpm

The speed of the generator is calculated as:

$v_{s}=rw\\v_{s}=r(2\pi f)$

Substitute the given values

$v_{s}=(1.0m)2\pi (\frac{100}{60}rev/s )\\v_{s}=10.47m/s$

For approaching generator the frequency is calculated as:

$f_{+}=\frac{f_{s}}{1-\frac{v_{s}}{v} }\\f_{+}=\frac{600Hz}{1-\frac{10.47m/s}{343m/s} } \\f_{+}=620Hz$

On the other hand,for the receding generator,Doppler's effect is expressed as:

$f_{-}=\frac{f_{s}}{1+\frac{v_{s}}{v} }\\f_{-}=\frac{600Hz}{1+\frac{10.47m/s}{343m/s} } \\f_{-}=580Hz$

Therefore the the highest frequency is 620Hz and lowest frequency is 580Hz

8 0

3 years ago

Which of these planets is the odd one out based on their physical features?

Maurinko [17]

Answer:

mars

Explanation:

the planet that is the odd is Mars

7 0

2 years ago

A car engine supplies 2.0 x 103 joules of energy during the 10. seconds it takes to accelerate the car along a horizontal surfac

andrew11 [14]

Answer: 2. 2.0*10^2 W

Explanation:

Power = Work/Time

Power = (2.0*10^3) Joules/10 seconds

Power = 2.0*10^2 Watts

7 0

2 years ago

Important minerals such as copper are found in what?

adoni [48]

It can be found in granitic and basaltic rock.

3 0

2 years ago

Determine the change in electric potential energy of a system of two charged objects when a -2.1-C charged object and a -5.0-C c

elena55 [62]

Answer:

Change in electric potential energy ∆E = 365.72 kJ

Explanation:

Electric potential energy can be defined mathematically as:

E = kq1q2/r ....1

k = coulomb's constant = 9.0×10^9 N m^2/C^2

q1 = charge 1 = -2.1C

q2 = charge 2 = -5.0C

∆r = change in distance between the charges

r1 = 420km = 420000m

r2 = 160km = 160000m

From equation 1

∆E = kq1q2 (1/r2 -1/r1) ......2

Substituting the given values

∆E = 9.0×10^9 × -2.1 ×-5.0(1/160000 - 1/420000)

∆E = 94.5 × 10^9 (3.87 × 10^-6) J

∆E = 365.72 × 10^3 J

∆E = 365.72 kJ

6 0

2 years ago