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Patdon10
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Homework Statement
A 100-g block hangs from a spring with k = 5.2 N/m. At t = 0 s, the block is .20 m below the equilibrium position and moving upward with a speed of 2.10 m/s. What is the block's speed when the displacement from equilibrium is .324 m?
Homework Equations
w0=sqrt(k/m)
x(t) = Bsin(w0*t) + Ccos(w0*t)
v(t) = w0Bcos(w0*t)-w0Csin(w0*t)
The Attempt at a Solution
I know the answer is 1.02 m/s, and I'm not getting that at all : /
w0=sqrt(k/m)
= sqroot (5.2/.100) = 7.2111 rad/s
x(t) = Bsin(0) + Ccos(0)
x(t) = B
v(t) = w0Bcos(0) - w0sin(0)
v(t) = w0B
1.9 = 7.2111B ---> B = 0.26348
x(t) = Bsin(w0*t) + Ccos(w0*t)
0.297 = 0.26348*sin(7.2111*t) + (0.2)cos(7.2111*t)
0.297 = 0.03307344t + 0.19841808t
0.297 = 0.2314915203t
t = 1.28298436
v(t) = [(7.2111)(0.26348)cos(7.2111*1.28298436)] -
[(7.2111)(0.2)sin(7.2111*1.28298436)]
v(t) = 2.418364634 - 0.2318690865
v(t) = 2.31869 m/s
Can anyone see what I'm doing wrong? Thanks in advance!