A mechanical piston in an engine oscillates with simple harmonic motion. The amplitude of the oscillation is 1.5 cm and it operates at a frequency of 40 Hz. At time t=0t = 0t=0, the piston is momentarily at rest at its maximum positive displacement from its equilibrium position.
Which expression gives the displacement xxx, in metres, of the piston at time ttt?
1.5cos(80πt)1.5 \cos(80\pi t)1.5cos(80πt)
0.015sin(80πt)0.015 \sin(80\pi t)0.015sin(80πt)
0.015cos(80πt)0.015 \cos(80\pi t)0.015cos(80πt)
0.015cos(40t)0.015 \cos(40 t)0.015cos(40t)
