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3 years ago

5

A millionairess was told in 1992 that she had exactly 15 years to live. However, if she immediately takes off, travels away from

the Earth at 0.8 c and then returns at the same speed, the last New Year's Day the doctors expect her to celebrate is:

1 answer:

mamaluj [8]3 years ago

7 0

Answer:

The expected year is 2017.

Explanation:

Total years that the millionaire to live = 15 years

Travel away from the earth at = 0.8 c

This is a time dilation problem so if she travels at 0.8 c then her time will pass at slower. Below is the following calculation:

$T = \frac{T_o}{ \sqrt{1-\frac{V^2}{c^2}}} \\T = \frac{15}{ \sqrt{1-\frac{0.8^2}{c^2}}} \\T = 25 years$

Thus the doctors are expecting to celebrate in the year, 1992 + 25 = 2017

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A car accelerates for 10 seconds. During this time, the angular

bagirrra123 [75]

Answer:

the angular acceleration of the car is 1.5 rad/s²

Explanation:

Given;

initial angular velocity, $\omega_i$ = 10 rad/s

final angular velocity, $\omega_f$ = 25 rad/s

time of motion, t = 10 s

The angular acceleration of the car is calculated as follows;

$a_r = \frac{\omega_f - \omega_i }{t} \\\\a_r = \frac{25-10}{10} = 1.5 \ rad/s^2$

Therefore, the angular acceleration of the car is 1.5 rad/s²

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What is the potential energy possessed by a rock of mass 4kg projected to a height of 2m (g=10m/s2)

Mumz [18]

Potential Energy = Mass * Gravitational Constant * Height

What We Don't Know: Potential Energy

What We Know:

Mass

Gravitational Constant (9.8 m/s)

Height

Ep = mgh

Ep = 4 * 9.8 * 2

Ep = 78.4 Joules

The Potential Energy of the Rock is 78.4 Joules, based on the given information! Hope this helps you!

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Which two of the following reduce the background noise in magneto- medicine?

horrorfan [7]

Answer:

The answer is b.) and d.)

Explanation:

The options to reduce the background noise in magneto-medicine are given as follows:

a.) Orienting the heart parallel to the Earth's field

- This will have no significant effect on the measurements.

b.) Taking the difference of two nearby sensor measurements (gradiometer).

-This answer is TRUE.

c.) Placing the heart in a perpendicular fashion to the Earth's magnetic field.

_ This answer also will not have any significant effect on measurements.

d.) Using physical means to shield environmental fields.

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Some runners have just started a race. They began at rest and are getting faster.What statement best describes the motion of the

olasank [31]

Answer:

B

Explanation:

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A two-turn circular wire loop of radius 0.63 m lies in a plane perpendicular to a uniform magnetic field of magnitude 0.219 T. I

Basile [38]

Answer:

The magnitude of the average induced emf in the wire during this time is 9.533 V.

Explanation:

Given that,

Radius r= 0.63 m

Magnetic field B= 0.219 T

Time t= 0.0572 s

We need to calculate the average induce emf in the wire during this time

Using formula of induce emf

$E=-\dfrac{d\phi}{dt}$

$E=-B\dfrac{dA}{dt}$

$E=-B\dfrac{A_{2}-A_{1}}{dt}$

$E=B\dfrac{A_{1}-A_{2}}{dt}$ .....(I)

In reshaping of wire, circumstance must remain same.

We calculate the length when wire is in two loops

$l=2\times 2\pi\times r_{1}$

$l=2\times 2\pi\times 0.63$

$l=7.916\ m$

The length when wire is in one loop

$l=2\pi\times r_{2}$

$7.916=2\times \pi\times r_{2}$

$r_{2}=\dfrac{7.916}{2\times \pi}$

$r_{2}=1.259\ m$

We need to calculate the initial area

$A_{1}=N\times\pi\times r_{1}^2$

Put the value into the formula

$A_{1}=2\times3.14\times(0.63)^2$

$A_{1}=2.49\ m^2$

The final area is

$A_{2}=N\times\pi\times r_{2}^2$

$A_{2}=1\times\pi\times(1.259)^2$

$A_{2}=4.98\ m^2$

Put the value of initial area and final area in the equation (I)

$E=0.219\dfrac{2.49-4.98}{0.0572}$

$E=-9.533\ V$

Negative sign shows the direction of induced emf.

Hence, The magnitude of the average induced emf in the wire during this time is 9.533 V.

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3 years ago