A weight is oscillating on the end of a spring see figure Th
A weight is oscillating on the end of a spring (see figure). The position of the weight relative to the point of equilibrium by
Y= 1/12 (cos 8t - 7 sin 8t)
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We have given Y= 1/12 (cos 8t - 7 sin 8t) for 0<=t<=1
the times when the weight is at the point of equilibrium ( y =0) are the solutions to equation
1/12 (cos 8t - 7 sin 8t) =0
cos8t=7sin8t
by cross multiplication
1=7tan8t
tan8t=1/7
8t=arctan(1/7)=0.14189
8t=0.14189+k*pi radian
t=(0.1489/8)+k*(pi/8) where k is any integer
t=0.02+0.39k second since rounding to two decimal places
if 0<=t<=1,then the restrictions on k are
0<=0.0186+0.3926k<=1
-0.0186<=0.3926k<=1-0.0186
-0.0186<=0.3926k<=0.9814
(-0.0186/0.3926)<=k<=(0.9814/0.3926)
-0.04737<=k<=2.4997
k=0 or k=1 or k=2
the times when the weight is at the point of equilibrium are
t=0.02+0.39k
when k=0
t0=0.02+0.39*0=0.02 s
when k=1
t1=0.02+0.39*1=0.41 s
when k=2
t2=0.02+0.39*2=0.8 s
t={0.02,0.41,0.8}

