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konstantin123 [22]
3 years ago
5

A starship travels to a planet that is 20 light years away. The astronauts stay on the planet for 2.0 years before returning at

the same speed and they are greeted back on earth 52 years after they left. Assume that the time needed to accelerate and decelerate is negligible. How much have the astronauts aged? (a) 15 years, (b) 20 years, (c) 22 years, (d) 30 years, (e) 32 years.
Physics
1 answer:
ad-work [718]3 years ago
4 0

Answer:

astronauts age is 32 years

correct option is e 32 years

Explanation:

given data

travels = 20 light year

stay = 2 year

return = 52 years

to find out

astronauts aged

solution

we know here they stay 2 year so time taken in traveling is

time in traveling = ( 52 -2 )  = 50 year

so it mean 25 year in going and 25 years in return

and distance is given 20 light year

so speed will be

speed = distance / time

speed = 20 / 25 = 0.8 light year

so time is

time = \frac{t}{\sqrt{1-v^2} }

time =  \frac{25}{\sqrt{1-0.8^2} }

time = 15 year

so age is 15 + 2 + 15

so astronauts age is 32 years

so correct option is e 32 years

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The current in a series circuit is 19.3 A. When an additional 7.40-Ω resistor is inserted in series, the current drops to 13.4 A
Bogdan [553]

Answer:

16.8ohms

Explanation:

According to ohm's law which states that the current passing through a metallic conductor at constant temperature is directly proportional to the potential difference across its ends.

Mathematically, V = IRt where;

V is the voltage across the circuit

I is the current

R is the effective resistance

For a series connected circuit, same current but different voltage flows through the resistors.

If the initial current in a circuit is 19.3A,

V = 19.3R... (1)

When additional resistance of 7.4-Ω is added and current drops to 13.4A, our voltage in the circuit becomes;

V = 13.4(7.4+R)... (2)

Note that the initial resistance is added to the additional resistance because they are connected in series.

Equating the two value of the voltages i.e equation 1 and 2 to get the resistance in the original circuit we will have;

19.3R = 13.4(7.4+R)

19.3R = 99.16+13.4R

19.3R-13.4R = 99.16

5.9R = 99.16

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R = 16.8ohms

The resistance in the original circuit will be 16.8ohms

5 0
3 years ago
1.A Radio station broadcasts modern song on medium wave 350 Hz every day at ten o’clock in the morning. The velocity of radio wa
love history [14]

Answer:

ans \:  = \boxed{{4.8 \times 10}^{ - 4}  Hz}

Explanation:

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klio [65]
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f is the frequency
\lambda is the wavelength
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