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I really need the answer to this pendulum problem ASAP. Thank you so much!

A pendulum of length L has a bob of mass M at the end of it. The bob is attached to a spring that has a force constant k. When the bob is directly below the pendulum support, the spring is unstressed. Derive an expression for the period of this oscillating system for small-amplitude vibrations (assume there is no displacement from the horizontal). Suppose that M = 2.80 kg and L is such that in the absence of the spring the period is 2.90 s. What is the force constant k if the period of the oscillating system is 1.45 s?

2007-07-06 08:29:16 · 4 answers · asked by YoDaddyHoe 1 in Science & Mathematics Physics

4 answers

Displacement of the bob x.
Angle of inclination α = x/L.
Force acting on the bob:
F(x) = -kx - Mg(x/L) = - (k+Mg/L)x

Dynamic equation:
Ma = F(x)
M d²x/dt² + (k+Mg/L)x = 0
d²x/dt² + (k/M+g/L)x = 0
d²x/dt² + ω²x = 0, where
ω² = (k/M+g/L)

****************** *************
T = 2π/ω = 2π/√(k/M+g/L)
****************** *************

Now:
2π/T = ω = √(k/M+g/L)
(2π/T)² = (k/M+g/L)
∆(2π/T)² = k/M


Answer:
k = (2π)²M ∆(1/T)² = 39.43 N/m

2007-07-06 09:36:38 · answer #1 · answered by Alexander 6 · 0 0

T = 2pi / angular frequency

for the period

There are obviously a couple of forces here to consider. You will need to consider these before attempting to do any of the problem, I think

Hooke's law for the spring (H)
The weight of the Bob (w = mg)

2007-07-06 09:31:15 · answer #2 · answered by Anonymous · 0 0

If A is the backside part of the pendulum, from the regulation of conservation of capability Kinetic capability at A = ability capability at 0.a hundred and fifty m above A Or a million/2 mV^2 = mgh Or V = sqrt (2gh) = sqrt (2 x 9.8 x 0.a hundred and fifty) = a million.715 m/s

2016-11-08 08:30:02 · answer #3 · answered by Anonymous · 0 0

How can the spring be unstressed when the bob is directly below the pendulum support?

2007-07-06 09:37:51 · answer #4 · answered by farwallronny 6 · 0 1

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