Question

Can someone help me with this Physics question please?

Answer 1

How many half-lifes is 49.2 years ?

(49.2 years) / (12.3 years per half-life)  =  4 half-lifes.

In 4 half-lifes, (1/2) · (1/2) · (1/2) · (1/2) of the original sample remains.

That's (1/2⁴) or (1/16) of the original.

(1/16) of 48.0 mg  =  3 mg .

=======================

Step-by-step:

== Start with 48 mg .

== After one half-life, 24 mg remains.

== Then, after the second half-life, 12 mg remains.

== Then, after the third half-life, 6 mg remains.

== Then, after the fourth half-life, 3 mg remains.

Answer 2

Answer:

Explanation:

The formula for this, the easy one, is

$N=N_0(\frac{1}{2})^{\frac{t}{H}$ where No is the initial amount of the element, t is the time in years, and H is the half life. Filling in:

$N=48.0(\frac{1}{2})^{\frac{49.2}{12.3}$ and simplifying a bit:

$N=48.0(.5)^4$ and

N = 48.0(.0625) so

N = 3 mg left after 12.3 years