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How to find mass from kinetic energy graph?
If you are given a kinetic energy vs time graph, for a particle doing SHM how do you find the mass? (maximum kinetic energy is 1.6 J and the period of the motion is 8 s if that helps)
1 Answer
- Steve4PhysicsLv 76 years ago
You can't do it unless you are told (or can find) the amplitude, A.
x = Asin(ωt)
v = dx/dt = Aωcos(ωt)
v² = A²ω²cos²(ωt)
KE = ½mv² = ½mA²ω²cos²(ωt)
The largest vaue of cos²(ωt)=1 and so
KEmax = ½mA²ω²
ω = 2π/T = 2π/8 = 0.7854 rad/s
1.6 = ½mA²0.7854²
from which you can find m if you know A.