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Homework Statement
A block is attached to a horizontal spring with k = 75 N/m undergoes SHM with an amplitude of 0.15m. If the speed of the block is 1.7 m/s when the displacement is 0.12m from equilibrium, what is the mass of the block?
Homework Equations
E = E'
E[itex]_{k}[/itex] = [itex]\frac{1}{2}[/itex]mv[itex]^{2}[/itex]
E[itex]_{s}[/itex] = [itex]\frac{1}{2}[/itex]kx[itex]^{2}[/itex]
The Attempt at a Solution
E = E'
E[itex]_{k1}[/itex] + E[itex]_{s1}[/itex] = E[itex]_{s2}[/itex]
[itex]\frac{1}{2}[/itex]mv[itex]^{2}[/itex] + [itex]\frac{1}{2}[/itex]kx[itex]^{2}[/itex] = [itex]\frac{1}{2}[/itex]kx[itex]^{2}[/itex]
Where subscript 1 indicates that x = 0.12 m and subscript 2 indicates that x = 0.15 m (max energy)
Substituting in ...
m = 0.21 kg
but the answer is 0.27 kg?