Temperature flows from __ to _

Potassium is a crucial element for the healthy operation of the human body. Potassium occurs naturally in our environment and th

Mariulka [41]

Answer:

a) 0.0288 grams

b) $2.6*10^{-10} J/kg$

Explanation:

Given that:

A typical human body contains about 3.0 grams of Potassium per kilogram of body mass

The abundance for the three isotopes are:

Potassium-39, Potassium-40, and Potassium-41 with abundances are 93.26%, 0.012% and 6.728% respectively.

a)

Thus; a person with a mass of 80 kg will posses = 80 × 3 = 240 grams of potassium.

However, the amount of potassium that is present in such person is :

0.012% × 240 grams

= 0.012/100 × 240 grams

= 0.0288 grams

b)

the effective dose (in Sieverts) per year due to Potassium-40 in an 80- kg body is calculate as follows:

First the Dose in (Gy) = $\frac{energy \ absorbed }{mass \ of \ the \ body}$

= $\frac{1.10*10^6*1.6*10^{-14}}{80}$

= $2.2*10^{-10} \ J/kg$

Effective dose (Sv) = RBE × Dose in Gy

Effective dose (Sv) = $1.2 *2.2*10^{-10} \ J/kg$

Effective dose (Sv) = $2.6*10^{-10} J/kg$

5 0

4 years ago

A police car moving at 36.0 m/s is chasing a speeding motorist traveling at 30.0 m/s. The police car has a siren that emits soun

maxonik [38]

Answer:

The frequency heard by the motorist is 4313.2 Hz.

Explanation:

let f1 be the frequency emited by the police car and f2 be the frequency heard by the motorist, let v1 be the speed of the police car and v2 be the speed of the motorist and v = 343 m/s be the speed of sound.

because the police car is moving towards the motorist at a higher speed, then the motorist will hear a increasing frequency and according to Dopper effect, that frequency is given by:

f1 = [(v + v2/(v - v1))]×(f2)

= [( 343 + 30)/(343 - 36)]×(3550)

= 4313.2 Hz

Therefore, the frequency heard by the motorist is 4313.2 Hz.

5 0

3 years ago

ichrome wire of cross-sectional radius 0.791 mm is to be used in winding a heating coil. If the coil must carry a current of 9.2

77julia77 [94]

Answer:

length is 23.228091 m

Explanation:

Given data

radius = 0.791 mm = 0.791 × $10^{-3}$ m

current = 9.25 A

voltage = 1.20 × 10² V

to find out

resistance and length of wire

solution

we know the resistance formula that is

resistance = voltage / current

resistance = 1.20 × 10² /9.25

resistance = 12.97

so resistance is 12.97 ohm

and length of nichrome wire formula is

length = resistance × area / specific resistance of wire

so specific resistance of wire we know = 1.1 × $10^{-6}$

and area = $\pi$ × r² = $\pi$ × (0.0791× $10^{-3}$ )²

area = 1.97 × $10^{-6}$

length = 12.97 × 1.97 × $10^{-6}$ / 1.1 × $10^{-6}$

so length is 23.228091 m

6 0

3 years ago

Am radio signals are broadcast at frequencies between 550 khz and 1600 khz and travel 2.99792 × 108 m/s. What is the shortest am

Rus_ich [418]

Answer:

187.37 m

Explanation:

The wavelength of an electromagnetic wave is given by:

$\lambda=\frac{c}{f}$

where

c is the speed of light

f is the frequency

We see that the wavelength is inversely proportional to the frequency: this means that the shortest am wavelength will occur at the highest am frequency, which is

$f=1600 kHz = 1600 \cdot 10^3 Hz$