Solving Exponential and Spring Constant Problems in Physics | Need Help?

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In summary, the individual is seeking help with some physics problems, specifically calculating the probability of decay of a substance in one second and finding the spring constant for a mass on a spring. They have provided some background information and equations, but are still confused and seeking assistance. They also mention using a less-than-ideal physics textbook.
  • #1
Jammy
My heads spinning help!

As usual I've left my work to the end of the holiday and after 2 hours of physics questions my head is in a spin... i have a cou[ple of simple quetions where i know the soluion isobvious but i can't get my had around the answers... would anyone be able to point me in the right direction so i can answer them?

Changes in exponential:
1) how wold i go about working out the probability of decay of a substance in 1 second.I have been given a half life and a decay rate.


Spring constants:
2) I have been given the mass of a spring and the time for oscillations --> how do i work out the spring constant? I know f=kx but i am really confused

Thanks :)
 
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  • #2


Changes in exponential:
1) how wold i go about working out the probability of decay of a substance in 1 second.I have been given a half life and a decay rate.
I'm not sure what you mean by a decay rate. Decay decreases exponentially with time, so it is not constant. Unless your decay rate was given in terms of t^2.

Anyway, if a sample has a half life of an hour, then an individual nucleus of the sample will have a 50% chance (or 0.5) of decaying in that time. All you need to do then is change that two hours to one second and you have the answer.

50% in two hours
25% in 60 minutes
25/60= 5/12% chance of decaying in one minute
divide by 60 again for probability in one second.

Hope that helps
 
  • #3
Sorry for the double post, but just wanted to say that the two hour half life I used as an example was just invented and you should replace that with the half life they gave you in the question and get down to one second in a similar manner to me.
 
  • #4


Originally posted by Jammy

Spring constants:
2) I have been given the mass of a spring and the time for oscillations --> how do i work out the spring constant? I know f=kx but i am really confused

I am confused, too. Are you sure you have been given the mass of the spring; or is it a mass hanging from a spring. The latter is the usual type of problem dealing with idealized springs. Look up period of harmonic motion in your text. You will find

T = 2<pi>(m/k)^(1/2)

Feel free to visit my website for more help.
 
  • #5


Originally posted by Jammy
... the probability of decay of a substance in 1 second.

... the mass of a spring and the time for oscillations --> how do i work out the spring constant?
It is not clear what is meant by the "probability of decay of a substance." Do you mean, "probability that a decay will occur in a substance composed of constituents that are prone to decay?"

You probably mean mass on the end of the spring. There is probably a formula in your book for this. Oh wait. Based on the two questions you asked which don't seem to have anything to do with each other, you're probably using the worst intro phys book I've ever seen. I don't remeber the author or title, but the ones that I have seen have a picture of a waterfall or something like that on the front. It gives extremely brief treatments of QM, thermo, relativity, and such in an extremely oversimplified manner, with utter disconnectedness. If that is the book you are using, I feel sorry for you.
 

1. What is an exponential function in physics?

An exponential function in physics is a function where the independent variable is an exponent. It is commonly used to describe processes that change at a constant rate, such as radioactive decay or population growth.

2. How do you solve an exponential function in physics?

To solve an exponential function in physics, you can use logarithms or graphing techniques. Logarithms can help you find the value of the exponent, while graphing can give you a visual representation of the function.

3. What is the spring constant in physics?

The spring constant in physics is a measure of the stiffness of a spring. It represents the amount of force required to stretch or compress a spring by a certain distance.

4. How do you calculate the spring constant?

The spring constant can be calculated by dividing the force applied to the spring by the amount of displacement it causes. It can also be calculated by dividing the potential energy stored in the spring by the amount of displacement.

5. What are some real-life applications of solving exponential and spring constant problems in physics?

Solving exponential and spring constant problems in physics is useful in many real-life applications, such as predicting population growth, determining the decay rate of radioactive materials, designing and testing springs in various mechanical systems, and understanding the behavior of elastic materials. It is also important in fields such as engineering, biology, and economics.

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