Question

Given the equation for simple harmonic method d=1.3cos(3pi/4 t) answer the following questions:

a)Find the maximum displacement.
1.i got 1.3

b)Find the frequency and length of the pendulum

c)Calculate the value of d when t=3
i got .919

d)Determine the least positive value of t for which d=0.
i got 2/3

Answer 1

(b)The period is

T=2π/(3π/4) = 8/3 s, so the frequency is 3/8 Hz

Now, use T=2π√(L/g) to find L

(d) since cos(π/2)=0, you want

3π/4 t = π/2
t = 3π/4 * 2/π = 3/2

Answer 2

for L i got 3.85