Body on a spring: expression for the period T

AI Thread Summary
The discussion revolves around deriving the period of vertical oscillations for a mass m suspended from springs with varying configurations. For a single spring, the period T is expressed as T = 2 π √(m / k). When two identical springs are arranged in series, the effective spring constant is halved, leading to a period of T = 2 π √(m / (k / 2)). In contrast, when the springs are placed in parallel, the effective spring constant doubles, resulting in a period of T = 2 π √(m / (2k)). The calculations confirm that the changes in spring configuration directly affect the period of oscillation.
moenste
Messages
711
Reaction score
12

Homework Statement


(a) A body of mass m is suspended from a vertical, light, helical spring of force constant k, as in Fig. 1. Write down an expression for the period T of vertical oscillations of m.

(b) Two such identical springs are now joined as in Fig. 2 and support the same mass m. In terms of T, what is the period of vertical oscillations in this case?

(c) The identical springs are now placed side by side as in Fig. 3, and m is supported symmetrically from them by means of a weightless bar. In terms of T, what is the period of vertical oscillations in this case?

2bda1af4ce78.jpg


2. The attempt at a solution
(a) The first figure looks like a basic example of a body on a spring and it's period should be: T = 2 π √(m / k).

(b) Since there are two identical springs, I would say that their force constant k should be less, because the spring is longer now: T = 2 π √(m / (k / 2)).

(c) Since the two springs are in parallel, the force constant k should be twice as much: T = 2 π √(m / (2k)).

I am not sure for the (b) and (c) parts. If we take the (a) formula as the basis, the only thing (as I see it) that changes is k due to the different spring positions. So, for (b) it should be (k / 2) and for (c) 2k. I am going in the right direction?
 
Physics news on Phys.org
moenste said:
If we take the (a) formula as the basis, the only thing (as I see it) that changes is k due to the different spring positions. So, for (b) it should be (k / 2) and for (c) 2k. I am going in the right direction?
Exactly right! :thumbup:
 
  • Like
Likes moenste
Thread 'Collision of a bullet on a rod-string system: query'
In this question, I have a question. I am NOT trying to solve it, but it is just a conceptual question. Consider the point on the rod, which connects the string and the rod. My question: just before and after the collision, is ANGULAR momentum CONSERVED about this point? Lets call the point which connects the string and rod as P. Why am I asking this? : it is clear from the scenario that the point of concern, which connects the string and the rod, moves in a circular path due to the string...
Back
Top