Daniel B. answered 05/18/21
A retired computer professional to teach math, physics
The question does not mention the units of time t.
But since in part c) seconds are mentioned, I assume that t is measured in seconds.
(a)
Amplitude A is the maximum displacement, which is the constant multiplying cos,
i.e., A = 0.52 m.
Period T is the value of t that makes the argument of the cos equal 2π.
That is, (π/4)T = 2π
T = 8 s
Frequency f is the inverse of period
f = 1/8 s-1
(b)
Velocity v is the derivative of displacement x, and
acceleration a is the derivative of velocity.
x(t) = 0.52cos((π/4)t)
v(t) = -0.52(π/4)sin((π/4)t)
a(t) = -0.52(π/4)²cos((π/4)t)
vmax = 0.52(π/4) = 0.4 m/s
amax = 0.52(π/4)² = 0.32 m/s²
(c)
x(2) = 0.52cos((π/4)2) = 0
v(2) = -0.52(π/4)sin((π/4)2) = -0.52(π/4) = -0.4 m/s
a(2) = -0.52(π/4)²cos((π/4)2) = 0