<h3>
Answer:</h3>
15.29 minutes
<h3>
Explanation:</h3>
<u>We are given;</u>
- Original number of counts = 1668 counts
- New number of counts = 1330 counts
- Time is 5 minutes
We are required to determine the half life of the sample;
- We know that half life is the time it takes for a radioactive sample to decay by a half of the original amount.
- To calculate the remaining mass after decay we use the formula;
- N = N₀ × 0.5^n , where N is the remaining amount, N₀ is the original amount and n is the number of half lives.
- Using the formula we can calculate the value of n;
1330 counts = 1668 counts × 0.5^n
Thus,
0.5^n = 0.79736
Introducing logarithm;
n log 0.5 = log 0.79736
Thus,
n = 0.327
But, n = time ÷ half life
Thus,
Half life = time ÷ n
= 5 minutes ÷ 0.327
= 15.29 minutes
Thus, the half life of the unknown sample is <u>15.29 minutes</u>
That 'band' around the globe is called the "Tropic Zone". It's the entire part of the surface of the Earth where the sun can ever be directly overhead.
Answer:
a) W = - 1.752 10⁻¹⁸ J, b) U = + 1.752 10⁻¹⁸ J
Explanation:
a) work is defined by
W = F . x
the bold letters indicate vectors, in this case the force is electric
F = q E
we substitute
F = q E x
the charge of the electron is
q = - e
F = - e E x
let's calculate
W = - 1.6 10⁻¹⁹ 365 3 10⁻²
W = - 1.752 10⁻¹⁸ J
b) the change in potential energy is
U = q ΔV
the potential difference is
ΔV = - E. Δs
we substitute
U = - q E Δs
the charge of the electron is
q = - e
U = e E Δs
we calculate
U = 1.6 10⁻¹⁹ 365 3 10⁻²
U = + 1.752 10⁻¹⁸ J
C would because its weight is lower than it's buoyant force
Different <u>ions</u> of an element have different numbers of electrons.
I think it is ions.