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Pavel [41]
3 years ago
8

PHYSICS PLEASE HELP!

Physics
1 answer:
Salsk061 [2.6K]3 years ago
3 0

Answer:

It would take two half-lives which would be 130days

The substance has a half-life of 30 minutes. There has been two cycles that have occurred.

idk the last one

Explanation:

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Which of the following mechanical waves has the most energy?
zhenek [66]
Gamma radiation has the greatest energy<span>. This </span>is<span> because gamma radiation </span>has the highest <span>frequency. </span>Energy<span> a frequency.

Hope this helps, 

kwrob</span>
8 0
3 years ago
From a vantage point very close to the track at a stock car race, you hear the sound emitted by a moving car. You detect a frequ
Alexandra [31]

Approximately 15 m/s is the speed of the car.

<u>Explanation:</u>

<u>Given:</u>

speed of sound - 343 m/s

You detect a frequency that is 0.959 times as small as the frequency emitted by the car when it is stationary. So, it can be written as,

f^{\prime}=0.959 f

\frac{f^{\prime}}{f}=0.959

If there is relative movement between an observer and source, the frequency heard by an observer differs from the actual frequency of the source. This changed frequency is called the apparent frequency. This variation in frequency of sound wave due to motion is called the Doppler shift (Doppler effect). In general,

                     f^{\prime}=\left(\frac{v+v_{0}}{v-v_{s}}\right) \times f

Where,

f^' - Observed frequency

f – Actual frequency

v – Velocity of sound waves

v_0 – Velocity of observer

v_s - velocity of source

When source moves away from an observer at rest (v_{0} = 0), the equation would be

                        f^{\prime}=\left(\frac{v}{v-\left(-v_{s}\right)}\right) \times f

                        f^{\prime}=\left(\frac{v}{v+v_{s}}\right) \times f

                        \frac{f^{\prime}}{f}=\left(\frac{v}{v+v_{s}}\right)

By substituting the known values, we get

            0.959=\left(\frac{343}{343+v_{s}}\right)

           0.959\left(343+v_{s}\right)=343

           0.959(343)+0.959\left(v_{s}\right)=343

           328.937+0.959 v_{s}=343

           0.959 v_{s}=343-328.937=14.063

           v_{s}=\frac{14.063}{0.959}=14.66 \mathrm{m} / \mathrm{s}

Approximately 15 m/s is the speed of the car.

3 0
3 years ago
B) A non-inductive load takes a current of 15 A at 125 V. An inductor is then connected
levacccp [35]

Answer:

i. 43.5 mH ii.  16 Ω. In phasor form Z = (8.33 + j13.66) Ω iii 58.64°

Explanation:

i. The resistance , R of the non-inductive load R = 125 V/15 A = 8.33 Ω

The reactance X of the inductor is X = 2πfL where f = frequency = 50 Hz.

So, x = 2π(50)L = 100πL Ω = 314.16L Ω

Since the current is the same when the 240 V supply is applied, then

the impedance Z = √(R² + X²) = 240 V/15 A

√(R² + X²) = 16 Ω

8.33² + X² = 16²

69.3889 + X² = 256

X² = 256 - 69.3889

X² = 186.6111

X = √186.6111

X = 13.66 Ω

Since X = 314.16L = 13.66 Ω

L = 13.66/314.16

= 0.0435 H

= 43.5 mH

ii. Since the same current is supplied in both circuits, the impedance Z of the circuit is Z = 240 V/15 A = 16 Ω.

So in phasor form Z = (8.33 + j13.66) Ω

iii. The phase difference θ between the current and voltage is  

θ = tan⁻¹X/R

= tan⁻¹(314.16L/R)

= tan⁻¹(314.16 × 0.0435 H/8.33 Ω)

= tan⁻¹(13.66/8.33)

= tan⁻¹(1.6406)

= 58.64°

3 0
2 years ago
Some help please ,.......
serious [3.7K]
It's c bro, .2x5 equals 1, which accounts for the 1m/s accelerations.
4 0
3 years ago
Read 2 more answers
Match the type of boundary with its characteristic.
olga_2 [115]

At Divergent boundary, Crust is created.

At Convergent boundary, Crust is destroyed.

At Transform boundary, Crust is neither created nor destroyed.

<h3>What occurs at Divergent, Convergent and Transform boundary?</h3>

A divergent boundary occurs when two tectonic plates move away from each other. At this boundary, new oceanic crust is created.

Convergent boundaries are those boundaries where two plates are pushing into each other. These boundaries are pushing one of the plates under the other and back into the mantle to melt.

Transform boundaries are places where plates slide sideways past each other. At this boundary, Crust is neither created nor destroyed.

Learn more about boundary here: brainly.com/question/14298823

#SPJ1

7 0
2 years ago
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