<span>3.2 grams
The first thing to do is calculate how many half lives have expired. So take the time of 72 seconds and divide by the length of a half life which is 38 seconds. So
72 / 38 = 1.894736842
So we're over 1 half life, but not quite 2 half lives. So you'll have something less than 12/2 = 6 grams, but more than 12/4 = 3 grams.
The exact answer is done by dividing 12 by 2 raised to the power of 1.8947. So let's calculate 2^1.8947 power
= 12 g / (e ^ ln(2)*1.8947)
= 12 g / (e ^ 0.693147181 * 1.8947)
= 12 g / (e ^ 1.313305964)
= 12 g / 3.718446464
= 3.227154167 g
So rounded to 2 significant figures gives 3.2 grams.</span>
<em>Inertia</em> is the property of all matter by which it tends to remain in constant, uniform motion until it's acted on by an external force.
Gravitational potential energy is energy.
The unit of energy is the Joule.
1 Joule = 1 kilogram-meter² / sec²
<h3><u>Answer;</u></h3>
Period = 1/17 seconds
<h3><u>Explanation;</u></h3>
- Wavelength is related to period by the expression:
<em>speed = wavelength / period
</em>
- If we are given the speed, then we can easily calculate the period at the wavelength of 20 m.
<em>Given the speed of sound wave as 340 m/s </em>
<em>Period = Wavelength/ speed</em>
<em> = 20 m/340 m/s</em>
<em> </em><u><em>= 1/17 seconds</em></u>
