Question

A body oscillates with SHM according to the equation ( in SI unit )

x = (5) cos [2πt + π/4].

At t = 1.5 s, calculate the (a) displacement and (b)velocity of the body.​

Answer 1

(a Displacement =
$5 \cos(2\pi(1.5) + \frac{\pi}{4} ) \\ = 5 \cos(3\pi + \frac{\pi}{4} ) \\ = 5 \cos( \frac{13\pi}{4} ) \\ \ = 5 \times (-0.707) \\ \\ = -3.53m$

(b) velocity =
$- 2\pi(5) \ \sin(3\pi + \frac{\pi}{4} ) \\ = 2\pi \times (-0.707) \\ = -4.442m/s$