Answer:
72,300 years.
Explanation:
- Initial mass of this sample: 504 grams;
- Current mass of this sample: 63 grams.
What's the ratio between the current and the initial mass of this sample? In other words, what fraction of the initial sample hasn't yet decayed?
.
The value of this fraction starts at 1 decreases to 1/2 of its initial value after every half-life. How many times shall 1/2 be multiplied to 1 before reaching 1/8? . It takes three half-lives or years to reach that value.
In certain questions the denominator of the fraction is large. It might not even be an integer power of 2. The base-x logarithm function on calculators could help. Evaluate
to find the number of half-lives required. In case the base-x logarithm function isn't available, but the natural logarithm function is, apply the following expression (derived from the base-changing formula) to get the same result:
.
Sound waves are known as longitudinal waves. Longitudinal waves are also known as compressional waves. These are waves that are made up of a series of compressions and rarefactions. In a longitudinal wave, the motion of the medium is parallel to the direction of the wave. While in transverse waves the motion of the medium is at right angles to the direction of the wave.
Acceleration = r w² radius r = 0.82 meter angular velocity w
4.7 = 0.82 w²
So w = 2.394 radians / sec
Time period T = time duration for completing one revolution = 2 π / w
= 2π / 2.394 = 2.624 seconds