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Hitman42 [59]
3 years ago
13

If We Start With 400 Atoms Of A Radioactive Substance, How Many Would Remain After Two Half-Lives?

Physics
2 answers:
Gnom [1K]3 years ago
6 0

Two half-lives produce (1/2) x (1/2) = 1/4 of the decaying substance.

There would still be  400  atoms.  But  300  would have thrown off
particles from their nucleuses, and only  100  would still be radioactive.


Marta_Voda [28]3 years ago
4 0
You basically take a half-life one at a time. The first half-live gets rid of 200 of the atoms, leaving you with 200. Then the second half life gets rid of 100 of the remaining atoms (half of the 200) leaving you with 100 atoms
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Desde una altura de 120 m se deja caer un cuerpo. Calcular a los 2,5 s i) la rapidez que lleva; ii) cuánto ha descendido; iii) c
stira [4]

Answer:

i) 24.5 m/s

ii) 30,656 m

iii) 89,344 m

Explanation:

Desde una altura de 120 m se deja caer un cuerpo. Calcule a 2.5 s i) la velocidad que toma; ii) cuánto ha disminuido; iii) cuánto queda por hacer

i) Los parámetros dados son;

Altura inicial, s = 120 m

El tiempo en caída libre = 2.5 s

De la ecuación de caída libre, tenemos;

v = u + gt

Dónde:

u = Velocidad inicial = 0 m / s

g = Aceleración debida a la gravedad = 9.81 m / s²

t = Tiempo de caída libre = 2.5 s

Por lo tanto;

v = 0 + 9.8 × 2.5 = 24.5 m / s

ii) El nivel que el cuerpo ha alcanzado en 2.5 segundos está dado por la relación

s = u · t + 1/2 · g · t²

= 0 × 2.5 + 1/2 × 9.81 × 2.5² = 30.656 m

iii) La altura restante = 120 - 30.656 = 89.344 m.

6 0
3 years ago
Two identical loudspeakers 2.30 m apart are emitting sound waves into a room where the speed of sound is 340 m/s. Abby is standi
Dimas [21]

Answer:

Abby is standing (4.5^2 + 2.3^2)^1/2   from the far speaker

D2 = 5.05 m from the far speaker

The difference in distances from the speakers is

5.05 - 4.5 = .55 m     (Let y be wavelength, lambda)

n y = 4.5

(n + 1) y = 5.05 for the speakers to be in phase at smallest wavelength

y = .55 m          subtracting equations

f = v / y = 340 / .55 = 618 / sec     should be the smallest frequency

8 0
3 years ago
A Scooter travelling at 10m/s speed up to 20m/s in 4 sec.find the acceleration of scooter​
stira [4]

Answer:

2.5 m/s²

Explanation:

Given,

Initial speed ( u ) = 10 m/s

Final speed ( v ) = 20 m/s

Time ( t ) = 4 seconds

To find : Acceleration ( a ) = ?

Formula : -

a = ( v - u ) / t

a = ( 20 - 10 ) / 4

= 10 / 4

= 5 / 2

a = 2.5 m/s²

Therefore,

The acceleration of the scooter is 2.5 m/s²

7 0
3 years ago
Una secadora de cabello tiene una resistencia de 10Ω al circular una corriente de 6 Amperes, si está conectado a una diferencia
Gala2k [10]

Answer:

Una secadora de cabello tiene una resistencia de 10Ω al circular una corriente de 6 Amperes, si está conectado a una diferencia de potencial de 120 V, durante 18 minutos ¿Qué cantidad de calor produce?, expresado en calorías

5 0
3 years ago
Zak, helping his mother rearrange the furniture in their living room, moves a 60 kg sofa 5.9 m with a constant force of 40 N. Wh
Len [333]

Answer:236 J

Explanation:

Given

Mass of sofa m=60 kg

Displacement s=5.9 m

Force F=40 N

neglecting Friction

Work done is given by

W=F\cdot s

W=F\cdot s\cos 0

W=40\cdot 5.9

W=236 J

4 0
3 years ago
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