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Aliun [14]
3 years ago
14

An important news announcement is transmitted by radio waves to people sitting next to their radios 42 km from the station and b

y sound waves to people sitting across the newsroom 9.26 m from the newscaster. Taking the speed of sound in air to be 343 m/s, who receives the news first?
Physics
1 answer:
Alik [6]3 years ago
8 0

Answer:

news will reach to the listener who are 42 km apart

Explanation:

given,

distance of the radios from the station = 42 Km

speed of the sound in the air = 343 m/s

distance of the people = 9.26 m

time =\dfrac{distance}{speed}

time taken by the signal to reach to the radio

speed of the electromagnetic wave to reach to the people

speed of electromagnetic wave = 3 × 10⁸ m/s

t =\dfrac{42000}{3 \times 10^8}

t = 1.4 μs

time taken to reach to the people

time =\dfrac{distance}{speed}

t =\dfrac{9.26}{343}

t = 27 ms

time taken by the station to radio is less.

hence, news will reach to the listener who are 42 km apart

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A 4.6-kg block of ice originally at 263 K is placed in thermal contact with a 15.7-kg block of silver (cAg = 233 J/kg-K) which i
Viktor [21]

Answer:

temperature at  326.44 K system achieve equilibrium

Explanation:

given data

mass of block of ice = 4.6 kg

temperature = 263 K

thermal contact =  15.7-kg

specific heat of silver  cAg = 233 J/kg-K

initially temperature = 1052 K

to find out

what temperature will the system achieve equilibrium

solution

first we consider final temperature of the system  is T

we know that specific heat of water (C w) = 4186 J(kg K)

and

specific heat of ice ( C i )  = 2030 J/(kg K)

and

latent heat of fusion of ice ( Lf ) = 3.33 × 10^{5} J/kg

and we know that system is insulated

so  heat lost by silver = heat generated by ice    .................1

so we can say

mass of silver × specific heat of silver  × ( initial temp - final temp ) = mass of  ice × specific heat of ice  × ( ice temp ) + mass of  ice × latent heat of fusion of ice + mass of  ice × specific heat of water  × (final temperature )  

put here value we get

mass of silver × specific heat of silver  × ( initial temp - final temp ) = mass of  ice × specific heat of ice  × ( ice temp ) + mass of  ice × latent heat of fusion of ice + mass of  ice × specific heat of water  × (final temperature )

15.7  × 233 × ( 1052 - T ) = 4.6 × 2030 × 10 + 4.6 × 3.33 × 10^{5} + 4.6 × 4286 × ( T - 273 )

solve we get

T =  326.44 K

so temperature at  326.44 K system achieve equilibrium

7 0
3 years ago
If $1,800 is invested in a savings account offering interest at a rate of 4.5% per year, compounded continuously, how fast is th
Archy [21]

Answer:

The total amount  after 3 years is = $ 2054.10

Explanation:

Given data

Principal Amount (P) = $ 1800

Rate of interest (R) = 4.5 %

Thus the total amount after 3 years compounded annually is given by the formula =  P × [1 +\frac{R}{100}  ]^{3}

⇒ 1800 × [1 +\frac{4.5}{100}  ]^{3}

⇒ 2054.10

Thus the total amount  after 3 years is = $ 2054.10

Compound interest earned in three years = 2054.10 - 1800 = $ 254.10

3 0
3 years ago
What waves have high amplitudes
Olegator [25]

-- loud sounds

-- bright lights

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-- Slinkies that can pinch you painfully

-- a tsunami in the ocean

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5 0
3 years ago
The graph below shows the energy sources used to generate electricity in the United States.
DedPeter [7]

The correct answer is - D. 1 percent.

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5 0
3 years ago
Read 2 more answers
A ball is dropped from a building of height h. Assume the ball starts from rest and that air friction can be ignored. Derive an
agasfer [191]

Answer:

t=\sqrt{h/g}

Explanation:

We use the kinematics equation to solve this question:

y(t)=y_{o}+v_{o}t+1/2*a*t^{2}

v_{o}=0    because the ball is dropped

a=-g         the acceleration is the gravity, negative because it points downwards

y_{o}=h     initial height

y(t)=h/2     final height

So:

h/2=h-1/2*g*t^{2}

t=\sqrt{h/g}

8 0
3 years ago
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