11. Trait theory claims that

A 128 gram Radium-226 sample with a half-life of 2.25 billion years is found. How many grams will remain after two half-lives?

Bess [88]

Answer:

Option B. 32 g

Explanation:

From the question given above, the following data were obtained:

Original amount (N₀) = 128 g

Half-life (t½) = 2.25 billion years

Number of half-lives (n) = 2

Amount remaining (N) =?

The amount of 128 gram of Radium-226 that will remain after 2 half-lives has elapsed can be obtained as followb

N = 1/2ⁿ × N₀

N = 1/2² × 128

N = 1/4 × 128

N = 0.25 × 128

N = 32 g

Therefore, 32g of the sample will remain.

8 0

2 years ago

Cual es la velocidad de un atleta que recorre 800 metros en 2 minutos.

scoundrel [369]

<span>6.67 metros por segundo
~ Haga 800/120 que equivale a 6.67 porque hay 60 segundos en un minuto y hay dos minutos, entonces 60 veces 2 es igual a 180, luego configure su problema
</span>
Espero que esto te ayude:)

5 0

3 years ago

Read 2 more answers

Body mass index (bm) is a measure of body weight relative

kow [346]

BMI is a measure of body fat determined by ones Height, Weight, and Gender.

8 0

2 years ago

If a short-wave radio station broadcasts on a frequency of 9.065 megahertz (MHz), what is the wavelength of

Yakvenalex [24]

Answer:

If the radio wave is on an FM station, these are in Megahertz. A megahertz is one ... Typical radio wave frequencies are about 88~108 MHz .

Explanation:

To calculate the wavelength of a radio wave, you will be using the equation: Speed of a wave = wavelength X frequency.

Since radio waves are electromagnetic waves and travel at 2.997 X

10

8

meters/second, then you will need to know the frequency of the radio wave.

If the radio wave is on an FM station, these are in Megahertz. A megahertz is one million hertz. If the radio wave is from an AM radio station, these are in kilohertz (there are one thousand hertz in a kilohertz). Hertz are waves/second. Hertz is usually the label for the frequency of electromagnetic waves.

To conclude, to determine the wavelength of a radio wave, you take the speed and divide it by the frequency.

Typical radio wave frequencies are about

88

~

108

MHz

. The wavelength is thus typically about

3.41

×

10

9

~

2.78

×

10

9

nm

.

7 0

1 year ago

A 975-kg sports car (including driver) crosses the rounded top of a hill at determine (a) the normal force exerted by the road o

iVinArrow [24]

There are missing data in the text of the problem (found them on internet):
- speed of the car at the top of the hill: $v=15 m/s$
- radius of the hill: $r=100 m$

Solution:

(a) The car is moving by circular motion. There are two forces acting on the car: the weight of the car $W=mg$ (downwards) and the normal force N exerted by the road (upwards). The resultant of these two forces is equal to the centripetal force, $m \frac{v^2}{r}$ , so we can write:
$mg-N=m \frac{v^2}{r}$ (1)
By rearranging the equation and substituting the numbers, we find N:
$N=mg-m \frac{v^2}{r}=(975 kg)(9.81 m/s^2)-(975 kg) \frac{(15 m/s)^2}{100 m}=7371 N$

(b) The problem is exactly identical to step (a), but this time we have to use the mass of the driver instead of the mass of the car. Therefore, we find:
$N=mg-m \frac{v^2}{r}=(62 kg)(9.81 m/s^2)-(62 kg) \frac{(15 m/s)^2}{100 m}=469 N$

(c) To find the car speed at which the normal force is zero, we can just require N=0 in eq.(1). and the equation becomes:
$mg=m \frac{v^2}{r}$
from which we find
$v= \sqrt{gr}= \sqrt{(9.81 m/s^2)(100 m)}=31.3 m/s$

7 0

3 years ago