Simple Harmonic Motion for a block-spring system

AI Thread Summary
The discussion focuses on calculating the ratio of kinetic energy (KE) to potential energy (PE) for a block-spring system in simple harmonic motion (SHM) with a phase angle of π/5 radians. The formulas for PE and KE are provided, and the user attempts to solve for the ratio by substituting the phase angle into the equations. Initially, the user believes their calculations are correct but receives feedback indicating an error. The issue is resolved when it is discovered that the calculator was set to degrees instead of radians, confirming the importance of using the correct mode for accurate results. The conversation highlights common pitfalls in physics calculations related to angle measurements.
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Homework Statement



If the phase angle for a block-spring system in SHM is π/5 rad and the block's position is given x = xm cos(ωt + phi), what is the ratio of the kinetic energy to the potential energy at time t = 0?

Homework Equations



PE = (1/2)*k*[(max amplitude)^2]*cos^2(ωt + phi)
KE = (1/2)*k*[(max amplitude)^2]*sin^2(ωt + phi)

Solve for KE/PE in that form.

The Attempt at a Solution



I took KE and divided by PE, giving sin^2(phi)/cos^2(phi). Plugging in pi/5 for phi gives us 1.20253316E-4/.99987974669. However, the system is saying this is wrong . I do believe that I solved for KE/PE correctly. Any help would be much appreciated. Thanks very much!
 
Physics news on Phys.org
Have you set your calculator to RAD? pi/5 is in radians.

ehild
 
I knew I was doing it right! my calculator was in degrees...i hate it when that happens...thanks for helping me figure that out!
 

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